What is it about human body gas that boys and men find so funny? How do they have the ability to fart or burp on command? More universal questions that I will never know the answers to.
My children each have a container of stuff called Flarp. It is a gooey substance like silly putty, but softer. You push your fingers in it into the container at various speeds and it makes the most amazing realist fart sounds. The laughing involved in that is something else. Big huge belly laughs and smiles from ear to ear. Laughter until you start to hiccup, drool, and cry.
Then it's even more fun to blame every living thing in site for the farting noises. "Ew, mom, what have you been eating? Some farting foods?" followed by more bellows of laughter. Even the cats are not safe from blame.
The things that amuse cavemen. I'm sure cavemen were laughing at their farts and burps before they invented fire and the wheel. I wonder if the real cavemen played "Pull My Thumb"?