This guy and his girlfriend were going at it hot and heavy in the backseat of his car. A knock was heard on the window and there stood a cop. The guy got out, shaking like a leaf. The cop said that he wouldn't arrest him if he could be next.
The guy got back in the car and finished with his girlfriend. When he got out again, he was still shaking like a leaf. The cop said there was no reason to be scared, because he wouldn't arrest him if he could be next.
The guy said 'I'm not afraid that you'll arrest me, it's just that I've never done it with a cop before!"