He wanted to go where no man had gone before.
Explanation: This joke plays on Neil Armstrong’s famous line when he first set foot on the moon, “That’s one small step for man, one giant leap for mankind.” The humor lies in the twist, suggesting that Armstrong marked the moment by peeing, humorously claiming to “go where no man had gone before” in a very literal and personal sense—by urinating on the moon. The punchline adds a comical, unexpected twist to a historic event.