When you're making out with a girl with a paper bag
on her head, but you are uncertain as to what her face really looks like. This means her face is both beautiful and ugly at the same time.
Bro 1: I banged a chick last night, but someone had put a bag over her head.
Bro 2: Dude, you totally banged a chick with Schrodinger's Face.
Bro 1: Luckily I never took the bag off, so I'm going to assume she was decent.
Bro 2: Though it's equally likely she could have been fugly