Comedy is not a science, it’s an art. Therefore there are no rules and it can be very subjective. What one person finds funny another might gasp at.
One thing worth noting is that when analysing comedy and what is funny, it’s almost like it’s only visible out of the corner of your eye. As soon as you try and look directly at it and analyse it too much, all of the funniness disappears.
To me comedy is “Truth in Tragedy.” Not, “Tragedy and Time” as Woody Allen explained it. If the joke is funny, no matter when it’s told, it’s funny. I once heard a joke about 911 right after the bombing. It was hilarious! It didn’t make fun of the situation, it made fun of the comedian upon hearing the news. Funny is funny and that’s about it. -Jonathan