A crush on a girl based solely on the fact that she has a great pair of breasts.
A girl can tell if a boy/girl may have a boobie crush on her if
A) the boy/girl is constantly looking at her breasts during a conversation
B) is caught staring at her chest if he/she is bored
OR C) if he/she is always talking to his/her friends about the girl in question's breasts.
Boobie crushes are common among high school boys.
"Wow, James is checking you out again from the other side of the room."
"Yeah, it's probably just a boobie crush."
"True that. You're totally stacked."