Nick Cannon -- Mariah Carey & I Do the Dirty to Her Music

Mariah Carey's greatest hits just took on a whole new meaning -- because according to her husband Nick Cannon, when it's time for sex, the deed is done to her music.

Nick was on Howard Stern this AM when he revealed his lovemaking music of choice to the world ... and of course, Mariah is also on board.

It gets even weirder -- Nick also says he masturbates to Mariah's music ... and you'll never guess his favorite self-loving song.