The other day, I was in the office kitchenette, and two of my colleagues both named Paul happened to be there getting coffee. I quipped, "Oh no, is this legal? I think it's a violation of the Paul Exclusion Principle."
It was a horrible physics pun, perhaps one of the worst I've made in a long time. My challenge to you is to come up with an even worse one that you've told.
Note: You have to have actually made the pun to an appropriate audience. No fair just making one up for the purpose of the challenge.