"Mansize Rooster" is a song by English rock band Supergrass, released as the second single from their debut album, I Should Coco (1995).

Emma Cochrane from Smash Hits gave "Mansize Rooster" four out of five, writing, "Blasting into another floor-stomping, rocking track with searing vocals, Supergrass have all the appearance of a gang of schoolboys who have gleefully discovered that they can write pop songs and get paid for it.

Scenes of the band in an entirely white room playing their instruments, dancing crazily, jumping around in front of a mirror and holding up screens of each other are shown.

By this point all three members of Supergrass are sitting together in the bathtub naked, flicking each other with water and pulling faces.

During one of the final choruses, Mick and Danny lift a screen up in front of Gaz and he 'transforms' into a woman (in drag with a white-blonde wig, lipstick, a beauty spot and false breasts).