I once knew someone that would brag to me about their intelligence (and talk to me dismissively, as if I wasn't as smart as her). When I first met this person, they said they obtained a 99.95 percentile ranking for their high school exams, putting them in the top .05% of the country.
However recently I found out that this person didn't receive a 99.95, but rather a 99.2.
In other words, even though she was belittling my intelligence, her own score was lower than my score of 99.65!
I now think anyone who brags about themselves is deeply insecure and probably stupid.