My grandma once yelled at me and started treating me like a psychopath because i laughed when my brother slipped down the stairs. He was completely fine and just had some carpet burn, and EVERYBODY falls down those stairs all the time. And then it turns out that she told a bunch of people about how i laughed when he fell down the stairs, and how my uncle said that it 'Was not funny.".
I don't give a shit. Even i laugh when i get hurt. And there is actually some psychology to why some people laugh when they or others get hurt.