Ok, so, whenever someone hits me I start to laugh, not because it does't hurt, it does, but I also have a really hight pain threshold which means I can take a beating. I just think it's funny I guess? That cannot be normal. Well, I don't laugh if I'm in a bad mood. But if they take me down to the ground and continue hitting me i laugh especially hard, I can't stop myself. This only happens when I'm rough housing with friends or family members, it has yet to happen while I'm in the boxing ring, but I have slipped out the occasional chuckle.
Not that I was happy or amused at all I just think it is your minds way of dealing with something bad. Years ago I had a girlfriend who did the exact same thing so I know I'm not the only one.