So I was a sucker for a Forbes click-through list of "Ten Guaranteed Ways To Appear Smarter Than You Are" because I felt sure one of them would be: Listen to what other people say.
I think people are vain, and if you look like you understand and value what they are saying, they'll judge you to be smart.
I hate the multi-page format, but my desire — my vain desire — to see my answer in the set caused me to click all the way through to the end.
The advice includes stuff like wearing glasses and using a middle initial, but #1 is "Skip that drink." That surprised me. I had to laugh. Not drinking isn't a way to appear smarter than you are. It's a way to avoid actually becoming dumber.
You know, sometimes you might actually want to become dumber. But that's material for a different list: 10 Situations in Which You Would Be Better Off If You Weren't So Smart, 10 Reasons Why You Might Want to Take the Edge Off Your Intelligence, etc.
To be fair to Forbes, reading the fine print, I see that "Skip that drink" goes beyond advising you not to drink. It says that even holding a drink causes other people to lower their assessment of your intelligence.