Dean, Sam, Cas, and you were all in the impala, driving to Bobby's place to talk about a case.

Dean and Cas were in the front seat talking to each other about possible motives for the case, while you and Sam were both in the backseat, listening.

You slowly started to fall asleep from the boring conversation happening in front of you. Sam noticed and knew for a fact that you were exhausted. He silently watched as you fell asleep.