Thanks @DesertDave for asking. I base my answer on personal observation and experience. Since I am quite familiar with the humorous side of people, I understand that some people have very low threshold for funny things. They can absorb trigger so fast that their laughing appears abrupt, spontaneous and to some ill-timed and not according to the situation. They do not have control on that. That does not mean that they are insensitive and have inane behavior. No. They are hit by the trigger, they respond before applying brakes.

Suppose I slipped badly in rain in a funny way; one of the onlooker is of the type mentioned above. Laughing heartily would be the natural original response. When I tell them that I have unfortunately dislocated hip joint and I need help, they will be the first ones to come to the aid. . . . So, they are basically normal and good people.

If you are like that and you feel guilty, you may apologize and that will prove that you are not at all a bad person.