When someone trips and falls, I don't laugh ... unless they're laughing (because laughter is contagious) or they're goofy and hammy as they get up.
Side story: My first year of teaching, I was trying to navigate down an aisle in my first period class when my foot caught on a backpack strap. Boom! Down to my hands and knees. (Not a total face-plant.) I laughed. My students freaked out wondering if I was okay, especially the very remorseful owner of the backpack. Those were good kids.
I'm not amused by the lewd, crude, and rude. It falls flat for me. This explains why I see very few so-called comedies.
Pranks where the goal is to humiliate the target? So not funny to me.
Lest you think I'm too saintly and need to get back to polishing my halo, I am a fan of sarcasm. But I try to be careful with how I use it, only engaging with people I know well enough. They need to know I'm being sarcastic and that I'd never mean it in a hurtful way.
Witty comebacks and good-natured verbal sparring can be very funny. Clever wordplay. Well-placed irony.
Often what I find funny is the unexpected, the things that come out of nowhere. Maybe that seems like a contradiction, because an algebra teacher getting her ankle ensnared by a wily backpack certainly qualifies as unexpected. Like I said, since I was laughing, I really wouldn't have minded if the kids had laughed, too.
I guess I don't like the idea of being amused at someone else's expense. That makes blanket statements tough, because situations that look similar on the surface might affect the people involved in very different ways.
So next time your math teacher trips and falls, ask if she's all right, give her a hand, and help her laugh it off.