Immature Yet So Funny

Ok so I am one of those people who find the strangest things funny. Something will happen that’s really funny and everyone is laughing so hard and I don’t really get what they are laughing at. Then something happens that’s not so funny and people just giggle or smile, and I am almost peeing my pants. They always have to turn to me and be like “Franca…it’s not that funny, calm down.” So what is it that makes different things funny? How are peoples sense of humor different. Is it how people are brought up? Or what they have been exposed to before?