Jokes can be dangerous.
No, really, think of it this way: Sure, you just started with a harmless joke about the Slide Mountain Ocean, and a fine joke it is. But how long before they work intercontinental Red Rover into the Kansas high school science curriculum?
What? Six thousand years is a helluvalot less than four and a half billion.
Detail of xkcd #1449, by Randall Monroe, 18 November 2014.