(n.) A mistake that cannot be rectified.
There's no point crying over spilt milk
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"
Something unimportant, especially the former significant other of the person you're now dating. Refers particularly to the casualties resulting from boyfriend/girlfriend stealing.
Oh, don't worry that Jen's glaring at you from across the room. She's just spilt milk anyway.
a situation beyond preventative measure; beyond control. "don't cry over spilt milk"
janet saw her man with another woman, delegated it spilt milk, and promptly hit on his best friend.
When you plan to shoot your cum on a chick and instead it goes on the bed, floor, sink, etc.
Guy:I'm sorry about the spilt mily baby.
Girl: Damnit i wanted it in my mouth!