"Tik Tok" (styled as "TiK ToK") is the lead single by American recording artist Kesha from her debut studio album, Animal. Co-written by Kesha, Benny Blanco, and Dr. Luke, the song was released digitally on August 7, 2009 and was sent to U.S. radio on October 5. Lyrically, the song speaks of attending a party one night, coming home half-drunk, and waking up the next morning surrounded by 'beautiful women'. The song has received mixed reviews from music critics with some praising its lyrics and celebration of party lifestyle. Others have criticized the song for sounding 'irritating', while it has been compared to other particular tracks performed by the likes of Lady Gaga, Kylie Minogue and Uffie.

"Tik Tok" was co-written by Kesha, Dr. Luke and Benny Blanco and was co-produced by Dr. Luke and Benny Blanco. The song took three takes to get right as Kesha jokingly "white-girl rapped" over the beat. At one point, she had wanted to rewrite the verses of the song because she did not think they were funny or clever.

In an interview with Esquire, Kesha described her songwriting process, saying that after a night out returning home half-drunk stumbling, she would usually write down a few words of a song. The next morning, she would wake up with the story wanting to be told. She related her songwriting process to "Tik Tok",

"One morning I just woke up, and I live in this house with I-don't-even-know-how-many roommates — it's this Laurel Canyon house with seven rooms and roommates fluctuating monthly". She later added, "I woke up one day after we went to a party, and I was surrounded by ten of the most beautiful women you've ever seen. And I was like, I'm like P. Diddy — there's no man like this in the entire world. So that became the first line of the new single, and we just went from there. It's a daily process in my life."

Kesha elaborated on the theme of the song to PopEater,

"I just really wanted to embody the lifestyle that I live," [...] "We're all young and broke and it doesn't matter. We can find clothes on the side of the street and go out and look fantastic, and kill it. If we don't have a car that doesn't stop us, because we'll take the bus. If we can't afford drinks, we'll bring a bottle in our purse. It's just about not letting anything bring you down."

The song utilizes a minimalist "video-game beat" interspersed with handclaps and synths. It is sung in the chorus and rapped in the verses, enhanced by Auto-Tune in some places and features a line by Diddy.

"Tik Tok" was used to promote season six of Project Runwayand was featured in the 2009 reboot of Melrose Placeand on an episode of The Hills. The first televised performance of the song was a part of MTV Push, a program broadcast on MTV Networks worldwide. Kesha also performed the song at the 2009 Z100 Jingle Ball held on December 11 in Madison Square Garden. To promote the album Animal, she made appearances on the It's On with Alexa Chung, The Wendy Williams Show, Lopez Tonight, Late Night with Jimmy Fallon, The Tonight Show with Conan O'Brienand The Ellen DeGeneres Showto perform the song. The song was featured in the movie Percy Jackson & the Olympians: The Lightning Thief.

The song received mixed reviews, with the most positive coming from Kelsey Paine of Billboardwho said the song was "a love letter to DJs everywhere, with hand claps that build to a crescendo of pure, infectious dance-pop." Jim Farber of the New York Daily Newscalled the song "a vintage lick of dance candy too tooth-rottingly sweet to resist." Fraser McAlpine of the BBC gave the song four out of five stars, noting its similarities to "Just Dance" and their partying subject matter, but concedes that "[s]he does make it sound kinda fun though." He goes on to say that "Tik Tok" "ha[d] 'hit' written all over it" and that "you just can't see it cos it's too damn dirty." Billy Johnson, Jr. of Yahoo compared "Tik Tok" to the 80's L'Trimm hit, "Cars that Go Boom" and notes that Kesha has "take[n] on L'Trimm's vocal styling for her own hit." He elaborates, saying "[t]he L'Trimm influence on the song is obvious as Kesha borrows Lady Tigra and Bunny D's slurred cadence and airy persona."

Jonah Weiner of Slate Magazinegave the song a negative review quoting "The song sets up ship on the fault line between charmingly daft and deeply irritating." He then continued, making comparisons regarding other artists stating "The rapped verses are sub-Fergie-grade, proudly stuffed with groaners and to-hell-with-the-expiration-date slang." Weiner also made comment that the plotline plays a sequel to "Just Dance" by Lady Gaga: "girl wakes up drunk, stays drunk, finds a dance floor and (spoiler alert) gets even drunker." He noted that "Some listeners probably noticed a more-than-passing similarity between the song and "Pop the Glock", a minor 2006 club hit by the French-American sorta-rapper Uffie, who records for the small Parisian dance label Ed Banger." He then said the song "rides a minimalist, 8-bit-video-game beat; "Pop the Glock" is built around a snare drum machine pattern. Kesha's faux-bad-girl rhymes are tweaked by AutoTune; Uffie's faux-bad-girl rhymes are run through a vocoder effect, which supplies the song with its only hint of melody."

Jon Caramanica of the The New York Timesdescribed the song as "a zippy and salacious celebration of late nights and mornings-after." He noted that "[s]ome have compared Kesha, unfavorably, to Uffie, who is signed to the influential French electronic music label Ed Banger and whose sass-rap predated Kesha’s by a couple of years." He also postulated, "If anyone should feel fleeced by "Tik Tok", though, it’s Lady Gaga, who probably hears significant chunks of her hit "Just Dance" in its melody and subject matter." Comparing Uffie and Kesha, Complex said that "[i]t’s no doubt that Kesha’s strong, catchy vocals" were reminiscent of Uffie, but said that "her beats (created by Dr. Luke) veer more towards the over-produced sounds of Lady Gaga and Sean Kingston than the creative blips we hear from Uffie’s Ed Banger beatmakers."

Rohin Guha of BlackBook Magazinenoted similarities of the song with "Love At First Sight" by Australian pop singer Kylie Minogue, saying "We drew the conclusion that Kesha copped that song’s signature synth riff. More problematic, Team Kesha did a pretty lousy job covering up the theft. We weren’t alone in unearthing this stark similarity, however." He continued stating "Minogue didn’t employ the sound of Super Mario jumping over a koopa shell as a dance beat. And whereas "Tik Tok" is a song about promiscuity, "Love At First Sight" is about monogamous happily ever afters. But differences end there. Because once you identify "Tik Tok"'s riff as an almost beat-for-beat carbon copy of “Love“‘s driving force, it kind of takes the punch out of Kesha and a song so charmingly ridiculous in its ability to summit the American charts."

James Reed of The Boston Globesaid "Say what you will about last year’s big bubblegum anthems - from Miley Cyrus’s "Party in the U.S.A." to Lady Gaga’s string of pop confections - but compared to "Tik Tok", those songs are practically masterpieces written by Bob Dylan and produced by Phil Spector."

A parody of Tik Tok has been released by British band The Midnight Beast in January 2010. The parody charted in Australia and Ireland.

"Tik Tok" made its chart debut on the official New Zealand Singles Chart at number seven on the issue dated October 5, 2009. The following week, it moved up to number one. It held the top spot for a total of five consecutive weeks. The song also charted in Australia where it debuted on the ARIA Charts at number twenty-eight, and reached number one on its third week on the chart. In Europe, the song debuted at number thirty-eight in Sweden on the issue dated October 23, 2009 and managed to peak at number three. The song debuted at thirty-nine in Denmark and peaked at number six. In Norway, the song debuted at number eleven and peaked at number three. The song also charted in both the Flanders and Wallonia regions of Belgium, peaking at number four and one respectively. In Finland, the song debuted at number sixteen and peaked at number seven. It debuted on the official UK Singles Chart at number six on November 8, 2009 and over a period of just under three months climbed to a peak of number four on January 3, 2010 based on downloads alone. It has sold a total of 442,287 copies in the UK.

On the week ending October 24, 2009, "Tik Tok" made its debut on the Hot 100 at number seventy nine. It topped the chart on the issue dated January 2, 2010 as the first number one of the new decade, and so far topped the chart for nine consecutive weeks. This became the first number one solo single by the artist, and second overall after appearing on "Right Round" with Flo Rida earlier in 2009, although she was not officially credited. On the week ending December 27, 2009, the song broke records in the United States after selling 610,000 digital downloads, the highest ever by a female artist since tracking began in 2003 and second highest overall, behind "Right Round". It was reported on January 24, 2010 that "Tik Tok" has sold a total of 3 million downloads in the country alone.

"Tik Tok" made its first ever chart appearance in Canada, where the song debuted at sixty-seven on the Canadian Hot 100. It ascended to number one seven weeks after its debut, where it stayed for nine non-consecutive weeks.

The music video was directed by Syndrome and begins with Kesha awaking from a bathtub in a home as she stumbles out and begins to look for a toothbrush in the restroom. She makes her way down a staircase looking at the picture lining the wall. It becomes apparent that she isn't in her own house because she is not present in the family portrait hanging from the wall. Kesha makes her way to the kitchen, walking in on the family having breakfast startling them. She shrugs and then leaves the home as the family gets up and follows her. When she arrives at the sidewalk, she picks up a gold bicycle lying against a fallen fence and rides off. Kesha meets a group of children where she trades the bicycle for their boombox. The video cuts to another scene where she rejects a guy that is walking down the street and looking at her, and is picked up by a man portrayed by Simon Rex who drives her in a gold 1978 Trans Am. They are pulled over by the police who handcuff Kesha. The scene then pans to her singing while standing up in the convertible with the handcuffs hanging from one of her arms as she dangles it in front of the camera. The next scene showcases Kesha in an empty room filled with glitter. She then attends a party with Barry for the final scene. The video comes to an end with Kesha lying in a different bathtub from the one she woke up in. The gold car used in the video belonged to Kesha and the video was shot in Kesha's old neighborhood. The final party scene was shot at one of her friend's house they called 'The Drunk Tank'.