When you are about to finish in a girl's mouth when she doesn't want you to, so she
closes her mouth. Then you proceed to
blow your load all over her closed lips like a
dentist who's trying to get in someones mouth to clean but just gets pissed off.
Guy 1: "
How'd it go last night?"
Guy 2: "It was hilarious. My girl wouldn't open her mouth when I wanted to
finish. I couldn't wait any longer so I gave her the
impatient dentist."
