(n.) A mythical group of creatures used to explain missing beer from the fridge. It is commonly employed as an excuse from a less than honest roommate.
Person 1: "Hey did you see the beer I left in the fridge?"
Person 2: "No bro, why?"
Person 1: "I bought a case of it but now its totally MIA"
Person 2: "Looks like we have got a nasty infestation of beer snatchers in the apartment."