I don't remember all the details, but I think it was Day 1, and the guy opened up showing proof that Town lynches Mafia on Day 1 at a lower rate than the percentage of Mafia in the game. Therefore if everyone commits to voting random, they'll have a better chance to lynch Mafia. He wound up swaying some people to his argument, but the other half of the players didn't agree and had a big fight over it.
And yeah, if I recall, he earned some town credit for trying to metagame in a way that he "proved" was town-favorable, and won the game off of it.