There was once a trickster who loved pulling pranks on anything that’s alive.

He would swap bird eggs with ping pong balls and then laugh when the birds try to hatch those balls.

He would swap babies.  One time he swapped some lion cubs with rabbits.  You can imagine the chaos that resulted.

All the creatures were furious.  They got together and caught him.  They tried to make an off/on switch to put on him. 

Fortunately it did not work properly.  Instead of switching him off, it just sent a minor shock into his body.  This trigger was later known as the funny bone which we all inherited.

Image via Wikipedia