pants optional
Pants optional, if used at a party, actually means that pants are not allowed. All people must drop their trousers immediately (unless they have no underwear)
1: Why are you wearing pants?
2: Because my legs would get cold otherwise.
1: But it's pants optional.
2: Oh. (Drops pants)
2: Because my legs would get cold otherwise.
1: But it's pants optional.
2: Oh. (Drops pants)