Amanda: 'But how do you know you're bi if you're a virgin?'
Me: '... Why wouldn't I be able to tell?'
Her: 'But, you can't know you like guys until you've been with one...'
I ended up having to ask if a certain act 'qualified' one to be gay (or, in this case, bi)... And, well;
Me: "...I can kinda do that by myself... >.>"
She freaked out pretty hilariously at that point. It was also the last time she challenged me about it.