We're not sure, but it's a real brain twister. Maybe it's because the punchline is always the same, but the setup is different. Or maybe we're just laughing at our own reflections in the mirror.
Either way, it's a joke-oke to the absurdity of it all. Want to learn more about the physics of laughter? Click here!
Or, if you're feeling extra silly, check out our Laughter Club and join the ranks of the chronically amused.