When a guy comes too quickly during sex and the girl is left unsatisfied, it is common courtesy to offer to finish her off with the hands or mouth. It is also an act of pity if she was very close but the guy beat her to the finish line. Best undertaken without drawing attention to the fact that it is, in fact, out of pity.
Girl: oh yeah! oh my god, it's going to happen, i'm so close, aah aaah aaaaa-
Boy: -orgasms- im really sorry...
Boy: do you want me to finish you off?
Girl:i don't want your pity fingering... -sulk-