My wife once kneed me in the balls while I was locked and we were in the shower together. I was responsible for cleaning her and she thought I was trying to get fresh. Then I felt her knee slam into my trapped balls (hard). That was one of the hottest and most painful experiences I ever had. She didn't feel bad as she knows I like ballbusting, but I had to explain to her that busting with a cage on is dangerous. She's never done it again, but part of me sometimes wishes she would.