1. You're a cat person. A study in 2014 found cat people tend to score higher on intelligence tests than dog people. But dog people score higher in friendliness.
2. You've done DRUGS. Obviously they don't MAKE you smart. But a study in 2012 found kids with high I.Q.'s are more likely to try recreational drugs later in life. And they also drink more.
3. You're tall. A 2008 study found tall kids tend to score higher on tests than shorter kids do. Obviously that doesn't mean all short people are morons. You just might be slightly more likely to have a really high I.Q. if you're tall.
4. You're funny. A study in 2011 had people take tests to measure their reasoning skills. Then they had to write captions for "New Yorker" cartoons. Granted, "New Yorker" cartoons require a specific type of humor. But the smartest people in the study also wrote the funniest captions.