In the past year three people have made remarkably similar comments about the stupid crap I say. All were concerned/afraid of the stuff that I think but then decide not to share.
"It's hard to tell what you're thinking."
"Ah. Thanks, I guess."
"It's probably terrible, isn't it?"
The only person who sees me without this filter is, appropriately, my wife, who greets the uninterrupted flow with alternating giggles and disgust.
Real life example:
"A woman was hit by a bus today; she was 'apparently jogging'. How can you be 'apparently' jogging?"
"I'd imagine they felt it too recklessly presumptuous to assume she was skipping. Or they just assumed based on her jogging shorts and sport top. Probably said it so that people wouldn't jump to the conclusion that it was a suicide. Did she die?"
"No, she's in the hospital in critical condition."
This is where I would normally grunt thoughtfully and walk away. But familiarity has lowered my defenses.
"...I wonder what the treatment is for acute bus-itus."
"Well, obviously it's acute bus-itus. Chronic bus-itus would be if a bus backed over you slowly over a period of 10 years. That's not very common."
"They probably prescribe 'putting all your organs back in' and years of therapeutic 'not getting hit by buses'."
"Yes. This is true."
Drink icons taken from here: http://www.pixeljoint.com/pixelart/28897.htm. I'm a martini, wife is a glass of wine, and the margarita is an amalgam of three other people. Bonus for Matthew: