Joint pain caused by participating in activities with your bros.
Examples of such activities include but are not limited to: Sitting around playing video games for too many hours on end, injuring one's self during a "hold my beer" moment, or passing out in an awkward and/or uncomfortable place or position (like the back seat of a Volkswagen).
"Bruh...my Brositis is really acting up today after jumping out of Chad's window and sleeping in the bushes last night."
Fogey/fogy /fougi/ sl. (early 18C+, orig. Scot) old-fashioned, stuck-in-the mud.
Person with old fashioned ideas which he is unwilling to change: Come to the disco and stop being such an old fogey!
You think me an old fogeyand an old tory, his thoughtful voice said. I saw three generations since O’Connel’s time. I remember the famine. Do you know that the orange lodges agitated for repeal of the union twenty years before O’Connel did or before the prelates of your communion denounced him as a demagogue? You fenians forget some things. (James Joyce, Ulysses. PenguinBooks,1992. p. 38)