ha, found a reasonable answer on reddit. Unrelated to each other. Tits (birds) are called that because it's small, and tit (breast) is a corruption of teat. Boobies (birds) are thought to be stupid, so are named after the alternative term for idiot (boob), while booby (breast) is a corruption of bubby, which is either from the German bbbi (meaning teat) or as a result of baby talk (asking for "bubby/bubs" when it's hungry).