boo boo baby Share definition Flag An unexpected pregnancy or child. Also the best term to explain to your bastard child why Daddy never comes to visit. "Hey, have you seen Julie recently?" "Yeah, looks like she got knocked up with a boo boo baby." boo boo baby by Jack August 5, 2006 0 0 Get merch Get the boo boo baby mug. Buy Now — $32.95 See more merch