I also play tabletop games with a group of friends, but we usually play GURPS or Shadowrun. We've been playing for about a year and a half, but the only problem is that our usual GM can't really keep to one campaign for too long.

While this isn't necessarily a joke from a culture, my German grandfather always used to tell this joke: How do you fit a crocodile in a matchbox? (obligatory "I don't know, how?) Well, you need binoculars and tweezers. Then you hold the binoculars backwards and look at the crocodile, so it becomes really small. Then you pick it up with the tweezers and put it in the matchbox.

It's a horrible pun involving Immanuel Kant.