Case of the Ex

"Case of the Ex" (sometimes subtitled "Whatcha Gonna Do") is a song performed by American singer Mýa. It was written and composed by Christopher "Tricky" Stewart (with his songwriting partners Traci Hale and Thabiso "Tab" Nkhereanyne) for Mýa's sophomore studio record, Fear of Flying (2000). The up-tempo pop-R&B track was inspired by a relationship Hale was going through at the time. It was released on July 11, 2000, as the second single from the album, following "The Best of Me" (featuring Jadakiss).

The song received mixed reviews from contemporary music critics and became Mýa's breakthrough hit, both stateside and internationally. "Case of the Ex" became a top-five hit on the US Billboard Hot 100 for the week of December 2, 2000, peaking and spending three consecutive weeks at number two. Internationally, the single topped the Australian ARIA Singles Chart for two consecutive weeks in March 2001 and peaked at number three in the United Kingdom.

The accompanying music video for the single was directed by Diane Martel and choreographed by Tina Landon. The video, filmed in the Mojave Desert, featured the singer and her backup dancers performing with large poles as props, and dancing in the sand. The visuals drew comparisons to Janet Jackson's "You Want This" (1994) music video and Mel Gibson's 1979 film Mad Max. In addition, the video was nominated for a Washington Area Music Award for Video of the Year, while the song itself won in the Urban Contemporary Recording category in 2001.