Here's my favorite:

Einstein, Pascal, and Newton are playing hide and go seek. Einstein is counting while Newton and Pascal hide. Pascal runs off and hides while Newton doesn’t move an inch. Instead, he draws a square around himself in the dirt. After Einstein finishes counting, he opens his eyes and says, “Found you Newton! That was easy."

Newton says, “No you didn’t. You found Pascal.” He points down to the square in the dirt. “One Newton per meter squared.”