Girls , have you ever seen this type of reaction before?

yesterday I was fighting in a joking way with my friend, then I accidently kikced him in the nuts, he kinda lost his breath, his eyes rolled, and got paralized for 4 secnds and went on his knees without being able to speak properly, he almost cry. Was the first time that I saw a grown up man cry . I couldnt beleive that one kick could make him like that. its that normal to haapens with guys? any stories?