A lap dance from what you suspect to be a pre-op transexual.
Indicators of a trapdance might include failure to remove undergarments, obviously fake breasts, excessive hair, deep voice, or manhands.
"Hey man I think I just got a trapdance. She was grinding on me, but I saw her biceps bulging with delight under her thick arm hair. Then she went to whisper in my ear, and our adam's apples bumped."
Person 2: "My condolences."