Because they're funny on many levels.
A! U!!! If it doesn't make sense tell it so someone out loud. Pretty sure this is my first original joke
Wooden shoe like me to tell you.
Never mind...it's tearable
Oh, they'll tell you.
It would cause them to be disappointed on many different levels.
It lifts their spirits.
He who makes a mistake in an elevator is wrong on many levels.
Expectorant(/spoiler)