In the episode where Drew goes back to college and becomes friends with an older woman, there is a scene near the end of the episode which takes place during a bingo game. Drew is trying to talk his friend out of leaving him while drawing numbers for the game. At one point he draws a number and reads it off, then speaks about how he wishes he could have drawn B-4 so it would fit into what he wanted to say. He then draws another number which does turn out to be B-4.

The slipup is this: Look behind Drew at the number board during the scene. The numbers which are lit represent numbers which have already been drawn, and B-4 is already lit, so he couldn't have drawn it again.