A guy or girl who pretends to be
bisexual.
Often because they think it is
cool and also to gain attention from others (strangly normaly those of the opposite sex.)
Bi-trendy people
will often kiss but
will go no further sexualy unlike people who are really bisexual, this is mostly done around others as proof of how bisexual they are.
Bi-trendy people also have an obsession with talking about how bisexual they are and want everyone to know it.
Emos seem to be the best example of people who can be (but are not always) bi-trendy however anyone can be bi-trendy and i have seen it happen in many scenes.