an interesting twist on traffic

On the way home from shopping and dinner tonight, we got stuck in traffic. I know, you could have knocked us over with a feather. Anyway, it ended up being more congested than your run-of-the-mill traffic. E started to get impatient.

"Are we home yet?" she asked.
"No, E. We're trying to get there, but there's traffic," I replied.
"Why? Why is there traffic, mama?"
"Because someone had an accident and so now we're driving slowly," I told her.
"Well, let's hurry up and find out which girl had the accident. 'Cause I have to go potty too!"