When you and a boy are hooking up, but it's a complete secret and he sometimes acts like you're not.
"how long have you and him been hooking up?"
"like... a month"
"oh are you guys together?"
"no he's just my fake boyfriend"
"why does he treat you like that if you guys are hooking up?"
"because he's my fake boyfriend"
A boy that thinks and treats you as his girlfriend, but you are not. You let him buy you dinner and movies anyways.
" Are you and that boy dating?"
" No, hes just my fake boyfriend"