This is used to describe people who exclusively use Sitka branded gear, and think they are better than everyone else because of it. Sitka's motto, "sick for it" is a common hashtag people use on social media when posting about Sitka gear, hence the disease "Sick-for-it-itis" . People that suffer from this disease are usually cocky, and look down upon others because they spend thousands of dollars on mediocre, at best, gear.
"We knew Bobby had a strong case of Sick-for-it-itis when his entire instagram account consisted solely of Sitka gear pictures and #sickforit hashtags."
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. Penguin Books,1992. p. 38)