[opticks]

I prefer "ass antlers"

[Malacoda]

Or "whale tail," depending on the girth of the person.

Last week, I stopped into the library to return a few books, and saw a gal working there who was wearing a bikini top with low-rise jeans, and a lower back tattoo. The letters were hipbone to hipbone, four inches high, and said, "BOOTY."

She wasn't of the body type that required a labeling of the booty area, if you get my drift.

[Hazcat]

While "ass antlers" is quite humorous nothing really catches the essence, the feel or is as perfectly descriptive as "TRAMP STAMP"

[ccmay]

Nothing says "SLUT" like a tat on the butt.