1. a slang term for a navel, or bellybutton piercing. Derived from the way these piercings are often displayed with midriff baring tops by worn by females assumed to be permiscous.
see tramp stamp
That girl over there must be easy, shes wearing a belly shirt with her tramp clamp hanging out.
The act ladies perform when they bend over slightly and pull at the back of their too-short shirt. This is done in a vain attempt at modesty about their tramp stamp, and becomes an unconscious move.
Look at that girl doing the tramp clamp when she sits down.