Quotation Mark Mondays: Great jokes

Matt tried to tell Mark a joke: Why was six afraid of seven? Because seven eight nine!

Mark replied, "Really? Why would seven eat nine? Did that really happen?"
This led to a lengthy discussion about the mechanics of this particular joke, which managed to take the humor out of the whole gag.

Undeterred- and, in fact, inspired - Mark decided to write his own jokes:

Q: Which kind of trees get the sickest?

A: Ash trees, because they get emerald ash borer disease.

Q: Why are there restaurants?

A: Because people need stuff to eat.

Q: What did the dog do when he saw a lion?

A: He ran away.