I hate it when people shorten words that don't need shortening, and/or make up crappy nicknames for firearms... Case in point: My girlfriend's little brother just got an SKS. After owning it for 1 day, he deemed "SKS" was too long and began calling it his "SK". By day two, the arduous task of saying "SK" began to wear on him. It is now his "K".
While I'm on firearms related annoyances, I really hate hearing people reference "filing down the firing pin" as a method of converting a semi-auto rifle whenever they see an AR or AK in a gun shop. Yeah buddy, go ahead and file that thing down... it's probably better for us all that way anyway, mouth breather... I'll even let you borrow a file.