So a guy gets pulled over by a cop. The cop goes up to the car, notices the driver is alone and obviously drunk, eyes all red, head swaying from side to side.
Cop: " So you've been drinking tonight?"
Drunk: "No way, Officer, I'm the designated driver!"
Cop: "What do you think I am stupid, you're the only one in the car!"
Drunk: "....NOT!...check the trunk!"

joke courtesy Augie Tulba