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It's so easy to do in a chat room. I just do this: click here.
I want to capture that same benign, eye rolling, gently mocking disdain - but I have to stick to small words.
An example of an actual circumstance (true story) after which I might want to use such a phrase or word is when he ever-so-patiently explained to me that "rocket surgery" was an incorrect use of idiom.
Perhaps a quote?
I realize that this question is at least borderline for the site. If you feel I've crossed that line please edit if you feel that the question is salvageable.
EDIT: He's 56. Perhaps an instantly recognizable (to an American of his age) quote from pop-culture? Kind of like the way I might say, "Laugh it up, Fuzzball" to someone my age (46) who is very much enjoying the fact he's winning a card game?