One of the more common comments I (and I am sure others) get when people find out you play chess is "You must be smart to play chess" or "I'd love to play, but I'm not smart enough'. In an effort to encourage potential new players the response is normally "Oh, I'm not that smart" or "I've met plenty of dumb chess players" or of course "It's not that hard, really". This seems to have little effect in dispelling the notion that you have to be a brainbox to play, and I've often thought of tipping this on its head.
"Yes, I am smarter than you" or "Chess - only smart people play" are two such slogans I've come up with in this vein. Whether non-players would get the joke is probably unclear, although the fact they don't might actually prove the accuracy of the slogan.
To support the assertion that chessplayers do think better/faster/smarter than other people, here is an article by Ellie Kaufman titled "How Chess Players Brains Are Different From Everybody Else's" While some may dispute the veracity of some of the claims, the article does provide a summary of the various claims about chess thinking, and its effects on overall thinking and problem solving. Worth a read in preparation for the next dinner with your non chess playing friends.