This is in the episode where Spence gets a new girlfriend who cooks food for Doug.

About half way through the episode, Doug is having lunch with Deacon at work. Doug has a sandwich in a plastic bag. Throughout the scene, the sandwich is in and out of the bag several times. At one point, he has taken the sandwich out and laid it on top of the bag -- the next time you see the sandwich, it's back in the sealed bag.