Don't mind if I do
I phrase/saying to say while taking something that should have been, but wasn't, offered to you. Usually goes along with a deliberately rude gesture, like snatching something off a table.
At the Christmas Party, important guests were given a free tree ornament. Someone who was not supposed to get one walks up to their table and says abruptly "Don't mind if I do" and takes one of the ornaments for themselves.
Don't mind if I do
This is the last step for a successful oopst It's stealing something before you leave the house (usually D.V.D's) from a stranger you just blew your load on, while she is in the bathroom cleaning it off the cum. Make sure you won't see this bitch again. And if you do, try to oopst her again.
Man, I totally oopst that bitch and on the way out, I did a don't mind if I do and took some of her D.V.D's.