"Cum and done" refers to a woman who is willing to have sex for money (a hooker), but as soon as the guy cums, she is
immediately out of the mood, takes the cash, puts her clothes on and leaves.
As opposed to a more
expensive escort, who is paid by the hour, and even if the guy finishes after
five minutes, will stay with him to cuddle, kiss, wait for a second erection or even just to talk.