a phrase used to describe something especially shocking and/or awesome, a more extreme version of 'hands-down'.
Sally"That boy over there yonder in hands-down gorgeous"
Vicky"That may be true, but that man over there a ways is pants-down gorgeous"
Sally"Ooohh your right. Hands-down will not cut it when you have pants-down"
The penalty for losing a game of 8-ball (standard pool) without potting a single ball is to walk around the table with one's pants down (or skirt up), according to official pub rules. This counts for any loss, including accidental sinking of the eight ball.