party bi

A girl who acts bisexual, making out or engaging in sexual acts with other women, but only in the context of a male-centered crowd and usually when large amounts of alcohol have been consumed. Such a person, though it may appear otherwise on the surface, only takes heterosexual relationships seriously.

"Dude, did you see Jessica making out with that girl at the party? I didn't know she was a lesbian!"

"Nah, man, she's only party bi."

"NICE!"