When you push the head of you penis back into the shaft rolling it in. Then you tuck your rolled dick into your ballsack so that it looks like you have three balls.
Triceratops sex position is when your girl doggystyle on the bed, your under her with a finger in the anus, your wang in her thang, and a hand in her mouth, mimicking the Great Triceratops
Steve Irwin: Aye, crikey! Look at that Trickseratops in her natural habitat, isn't she a beaut? Notice the slutty clothes she is wearing in order to show off her engorged breasts and buttocks in order to attract mates that she will have drunk carefree sex with.