Q. Why are goths bisexual?
A. They can't tell either.
Problems only goths have: chatting up someone and trying to work out how to ask if they're a boy or a girl.
Worse problems only goths have: waking up next to someone after a night of passion and trying to work out how to ask if they're a boy or a girl.
(If that skirt looks really good on them, they're a boy and it's their girlfriend's.)