First time was when I 13. I had a gf who was 16. I had never been hit down there before so I never knew I was into it yet. So out of curiosity, I asked her to kick me. But she said no, that she only hit guys when provoked. So I provoked her by lifting her skirt up and kneeing her in the crotch. Of course that pissed her off. About half a minute later she recovered and got her revenge by pulling my jeans down and kneeing me. I fell to my knees holding my balls. She kicked me again while I was down and I fell on my side. She felt bad afterward and apologized to me. She offered to massage my balls and did so for a few seconds but it just caused them to hurt more so I told her not to do it.
I got a major hardon, so that was also when I realized I liked busting. So that was really a life-changing moment for me in a way.

