The verses and chorus of "You Shook Me All Night Long" are about two different peopleThe verses keep referring to the subject of the song using third person pronouns ("she was a fast machine", etc), yet the chorus is "you shook me all night long". The situation is that a man is boasting of his past exploits with a sexy young woman while his current girlfriend is around, and when he realizes she might be getting jealous he reassures her that this other woman didn't "shake him all night long" the way she did.
Or maybe the verses and chorus of "You Shook Me All Night Long" are about the same person after allThe man is still boasting about this hot woman he met once around his girlfriend, but he's really just teasing - in the chorus he reveals that he was talking about meeting her all along.
A third option would be that it's a perspective flipThe verses are by a man, while the chorus is by a woman. He shook her all night long, not the other way around. Double Entendre to imply that the guy likes to have sex with his clients, male or female, after offing whoever they want dead ("Come right in, forget about him / We'll have ourselves a ball" "For a fee, I'm happy to be / your back-door man").