Is it normal that i can smack my ballsack on my leg loudly that people hear it?

I can thrust my balls on my leg fast enough that it generates a sound. A sound that people in the same room can hear. I can gyrate at a fast motion. I can do it with boxers, briefs, Baggy shorts and regular shorts. Jeans are too tight, but you can definitely see the bulge. I manage to do it for about 10-20 secs, I try for 30secs., but it hurts my balls for that long enough period. Is it also normal that I do that because I think it makes my balls stronger?