Chronosexual

Not strictly bisexual but attracted to members of both genders depending on the time and situation. Behavior usually occurs when attempts to engage with the desired gender have failed. Typically examples include straight men who will go gay after a few drinks at a predominantly male venue; gay men who will embrace a girl because there is no better option i.e. other gay men in their presence; girls who kiss other girls for male attention.

Guy I: "Well, all the cute girls have left. Wanna fool around?"
Guy II: "Dude... sorry... not a chronosexual."
Guy I: "Man I'm way off schedule tonight."

by Rich Owl Rase August 12, 2009