It wasn't all the time, but about two sessions of every three he'd get bored and shit stir, to the point I could look at his face when I call his name and know he's about to do something "interesting".
I think he wanted to keep being a dumb half-orc because he didn't want to do anything in town or keep track of quests, but forgot that when you make a dumb character, its sort of boring.
I had him in a one-shot and an a megadungeon, and both times he came up with a wacky (but still could fit in the setting) character concept. Which was fine, except second session he'd get bored and go back to playing himself, and only remember the concept when it could be used to annoy people and derail the session
Before bringing him into a campaign, I told him "I like to have fun and make OOC jokes. You can make a fun or quirky character, but no matter their personality quirks they are going to be expected to behave like a rational person. Your megadungeon character was really pissing people off at the end and that shit will not fly in campaign, and not in the fun way."
Additionally stats didn't reflect him being a moron in town. 10 INT and I think 14 WIS (for saves).
There's a bit more to the story, moral of the story he did end up getting fired as a player.
And maybe thats just a case of bad DMing and I'm projecting because the only time I use that is when the player is being a little shit.