When someone tells you a slang term on i.m on myspace and do not know what it means so you quickly go to urbandictionary.com and look it up, hence urbandictionary emergency.
Rick:hey look at my new picture
Sally:Sure, go look at mine, pc4pc?
Rick: *oh shit what the fuck is pc4pc, oh noes urbandictionary emergency!
Sally:you still there
Rick: yeah, okay ill go comment now.*wow what a urbandictionary emergency.