Throw a baby at her face

An expression used when someone says or does something entirely stupid. The expression is related to someone having unprotected sex at a young age and getting knocked-up. Yeah, probably one of the stupidest things you could do. Getting knocked-up leads to babies, and so when someone says/does something really dumb, throw a baby at their face because if they want to do something that stupid, they'll probably end up doing even more stupid things like... oh, getting themselves pregnant. Just, don't really throw a baby at their face, it might harm the infant.

The "her" can be interchangeable to "his" or "their"

Girl 1: Nazis are Jews.
Girl 2: ... You're kidding me.
Girl 1: Aren't Nazis Jews?!
Girl 3: Just throw a baby at her face.