"Doh!" of the month

Earlier this month Ryan picked me up from the airport, and on our way home he gets behind a car in the fast lane.
"What the..?!" he asks no one in particular. "WHY ARE YOU GOING 45 MILES PER HOUR?!" he shouts at the car.
Just then, we pass the speed limit marker.
"Oh." he says. "Cuz the speed limit is 45."
I almost peed myself laughing.