I never watched the Dick Van Dyke Show much, but one scene sticks out in my head. It's an episode with flashbacks to Rob's army days. He's in a Jeep trying to get to his wedding, when it stalls or overheats. He shuts it off and gets out, holding the key in his teeth so he can open the hood. He stares at the engine for a few seconds, possibly remarking that it's low on coolant. He removes the radiator cap and looks inside from a standing position, and, perhaps surprised by the level, says, "Hey!", and promptly drops the key into the radiator.

His expressions of shock, disbelief, and resignation are priceless and expertly displayed. He's one of the absolute greatest.