When one uses one's big toe (right or left should work in an equally fine manner. Just choose your favorite!) to penetrate the anus of his or her partner.
Both big toes is called a coconut creme pie.
"If Steve really loved me, he'd bake me a long, jagged coconut creme pie until the early hours of the morn', but he's just been passing me the sloopy gilligan for like, two weeks. Guess I'd better kill myself. *raises noose*"