Slang to describe someone who's close to you(a friend) or likes to follow you around or is always with you. Can be use to describe your friends. They are the "batty" and you are the "bench" that they like to sit on or be around with. Batty i this slang means Ass and what do you do when you see a bench? YOU sit on it.
"Ya Reeta and I are batty on bench, we'll always together in school"
"batman and robin are batty on bench, you can't have one without the other"