In my mis-spent youth, I played a RPG called Paranoia. I and a group of like-minded friends were ensconced around a table in the back room of a local game-supply store. We were playing--i.e., one of us, the "GameMaster" had a fantastic situation in mind, and my friends took on the roles of characters in that situation. The GameMaster would describe the situation; the players would describe what they wanted their characters to do.
So I'm sitting at a table, waving my arms around and trying to enlist my fellow players in some scheme. I ask one of my friends something. He starts to answer, then gulps and stops talking. This isn't too strange. Paranoia can be kind of an intense game, and sometimes players seize up.
So I went on to the next player, asked him something. He'd been looking at his notes, doing some thinking. He started to tell me what he wanted his character to do. He looked up at me. And then he looked at a point over my left shoulder, and his eyes kind of unfocused. And then he stopped talking. I figured he'd seized up, too. I went on to the next player.
Each time I tried to talk to someone, they'd look at a point above my shoulder and clam up. I finally noticed this trend. I looked over my shoulder, and saw the backs of a couple of people who were ambling out of the room.
I asked what happened.
"That was Robin Williams," one of my helpful friends informed me. By now the famous comedian had disappeared.
Another friend sighed, "Maybe we should have asked him to play."
While Mr. Williams had been observing the game, he'd conversed with some other grown-up. I didn't notice at the time. Williams had asked, "So, what's the point of this game?"
"Survival in a hostile future run by a crazy computer, where you can't trust anyone."
"So, it's a game about aging," Williams replied. And left.
(Thanks to Arlene for remembering this better than I did.)