BAB is short term for bitch ass boy. A guy can be a BAB if he is immature or acts like a pansy. A BAB is usually always whining or complaining before he tries to help himself. A BAB is always feeling sorry for himself and tends to be a huge downer.
Girl #1: Ugh my ex got upset because it's been two days since I've texted him.
Girl #2: Really? Homeboy is such a BAB. Tell him to man up.
It all started on one small game in the year of 2016. It meant something small and chibi; something that's somewhat similar to chibi anime. You'll find that something to be cute, and adorable. You can set this term to pretty much anything you'd find adorably cute, and small.
It doesn't depend on age at all.
Example: "man, she's really cute and small. She's nice, and just perfect. She reminds me well of a bab."