'Big Time Rush' Star Stephen Glickman -- 'Cupcake Wars' Screwed Me With Gross Cupcakes

"Big Time Rush" star Stephen Kramer Glickman says he got royally screwed on "Cupcake Wars" as a guest judge ... because the cupcakes he reviewed were TOTALLY GROSS. Our photog caught up to the Nickelodeon star in Hollywood Friday night and he told…