It's a matter of context. If you go to a packed nightclub, you probably expect you're going to see some drunken behavior and some bumping-and-grinding, yes? Whereas you would be quite surprised to see people dancing wildly and sexually together in the middle of a bookstore, and they'd probably be asked to leave.

Many geek conventions have a strong perviness element. Men are walking around in tiny French Maid dresses. Women are walking around wearing nothing but liquid latex or tape. Girls and boys are dragging each other on leashes. Furries are wearing their suits. By a lot of standards this is already sexual behavior.