A front-facing tramp stamp. A decorative tattoo, positioned just above the pubic area and below the navel. A Falcon Crest can be a tattoo of any genre (i.e. traditional, tribal, etc.) but, like a tramp stamp is a wide, horizontal design, essentially symmetrical and positioned centered, between the hips.
The term references the TV show "Falcon Crest" which was a popular primetime soap opera from the '80s about a wealthy family in the California wine industry in the mold of Dallas or Dynasty - and may imply that the "above-the-pubes" location is a little "classier" than the tried and true lower back location of the tramp stamp.
On the family's first trip to the beach, Freddy was stunned to to see a prison-grade falcon crest peeking out from the top of his mother-in-law's bikini.