1. WTF. Slang. What the Fuck?! (used to express anger, impatience, surprise, fraud, etc.) 2. Rat's Nest. Slang. A situation or condition that is characterized by messiness, disorder, disarray, and/or confusion, many times unbeknownst to its creator. Commonly used to refer to something that is hopelessly convoluted and difficult to understand - analogous to how a rat might construct its nest (haphazardly and hastily thrown together from whatever materials happened to be readily available at the time). Usually an affront to looking normal on the surface to fool others, but disheveled in reality. "I tried to figure out what was causing the problem with the show, but there's a veritable rat's nest of fraud, stupidity, and cat hair down there." More definitions ?