Something mildly bad/unpleasant which has already happened, and nothing much can be done about. Usually referred to in the context of "stop crying over spilt milk".
"so you stuffed up a bit, stop cryin over spilt milk"
1. "She was giving me this great handjob.... and i spilt my children right there on the couch."
2. "I cant believe I spilt my children so quickly. It was quite embarrassing."