Some dork at work would mansplain to me.  I would make a joke such as, "and he was eating squid eyeballs!  It's like the Japanese lost a war or something to eat food like that."
And this ace dude would interject as everyone was having a hearty laugh, "well actually, they did lose a war.  It was known as . . . "  
He just sucked the air out of the room and ruined my hilarity.  I still fantasize about just punching him in the face and everyone ignoring it.