"At the time I thought it was a good idea to have sex with my ex-girlfriend. However, after we finished and she talked about starting the relationship again I had major boner's remorse."
A situation where a penis is starting to get hard, but is not solid, and at the same time, not completely flaccid. While a penis is in this state, anything could collapse the quantum wave, and render the penis either hard, or flaccid.
Dude, Jackie gave me this sexy look after our date, and until she came upstairs to my room, I had a Schrödinger's Boner.
or
I was this restaurant, and there was this waitress with a nice ass. Once she turned around and I saw here face though, I lost my Schrödinger's Boner.