If you’re driving down the street and you almost hit a squirrel running in the middle of the road, it’s not considered a squirrel anymore. What is it, you ask? A quirrel. Why? Because you just scared the “s” out of it.
This is something M’s dad said to him once, and he’s been repeating it ever since. He likes it because it’s funny and he’s never heard it told before, and no one he’s ever told it to has heard it either. It’s important to him because his dad made it up.
This joke is so lame it’s funny. You laugh because it’s kind of stupid, but as far as personally-made up jokes go, it’s pretty good. It’s not funny enough to be memorable, but funny enough to earn a little laugh.