I think about all the episodes where John's gotten hurt- even in "38 minutes" where he's having the life sucked out of him by the iratus bug thing and he's still making quips. There's this one moment where Rodney's whining about being screwed and for just a sec Sheppard breaks and says 'don't talk to me about being screwed' but then the shutters go back up and he's all 'macho leader man' again.

Like I said, I've put way too much thought into these boys! :)