If you think you heard it to describe a boy, then it's "Hey buddy" which means "Hey friend."

A bunny is a young rabbit. A 'bunny girl' is a sexually provocative waitress/hostess. The expression 'hey bunny' can be an expression of affection or interest, depending on context.

buddy = friend I will be mad if someone call me "bunny" :)

Buddy = pal = friend