About All In My Head (Flex) [feat. Fetty Wap]

"All in My Head (Flex)" is a song recorded by American group Fifth Harmony, featuring vocals by rapper Fetty Wap, for their second studio album, 7/27 (2016), which was released on May 27, 2016. It was produced by Stargate and Brian Garcia with additional production by Sir Nolan. Musically, "All in My Head (Flex)" is a reggae-trap song backed by synths, percussion, and guitar, containing an interpolation of the 1992 song "Flex" by Mad Cobra. The song was released as second single after a special encore performance on Xfinity following the 2016 Billboard Music Awards on May 22, 2016. The single was serviced to rhythmic contemporary radio stations in the United States on May 31, 2016.

Commercially, the song reached number 24 on the United States' Billboard Hot 100. The song also reached the top 40 in Australia, New Zealand, the United Kingdom, Canada and Ireland. To promote the song, the group performed on the season 22 finale of Dancing with the Stars. The song's accompanying music video, set on a tropical beach, was directed by Director X and premiered on the Vevo platform on June 23, 2016. "All in My Head (Flex)" won the category Song of Summer at the 2016 MTV Video Music Awards.