"Flex" is a song co-written and performed by Jamaican dancehall recording artist Mad Cobra, issued as the first single from his eighth studio album Hard to Wet, Easy to Dry.

[3] Mad Cobra stated that he was on a flight returning from New York, and was watching an exercise video on the in-flight entertainment system, and the lyrics "How this lady flex like she want to have sex?"

He wrote the lyrics for the song on an air sickness bag in his plane seat and took them to the studio when he arrived in Jamaica.

The song was meant to be an uptempo dancehall track in Mad Cobra's usual style, but became a slower R&B song when the backing tape accidentally slowed down and Mad Cobra slowed down his vocals to match the tape speed.

[2] The official music video for "Flex" was directed by Scott Hamilton Kennedy.