I Have A Brain

Preston climbed up on the counter to wash and dry his hands. As he was precariously walking along the counter top, the following conversation took place...

Mom: Preston, you be careful so you don't fall.

Preston: I won't fall mom. I will be careful.

Mom: Ok.

Then after he had gotten down and thought for a minute...

Preston: You know why I wouldn't fall, mom?

Mom: Why?

Preston: Because I have a brain.