Because it was dead.
I don't understand it, but I thought that joke was hysterical the first time I heard it.
Why did the monkey fall out of the tree?Why'd the other monkey fall out of the tree?
Because it was dead.
Why'd the third monkey fall out of the tree?
Peer pressure.
Why'd the cow roll down the hill?
It had no legs.
Ok, ok, I'll stop there...