From cool + -o- + -meter.
coolometer (plural coolometers)
- (informal) An imaginary device that measures coolness (the degree of fashionableness or popularity).
2009 December 7, Drew Perron, “Re: CONTEST: High Concept # 5”, in rec.arts.comics.creative[1] (Usenet):Hmmmmm. Robot centaurs are more awesome in a vacuum, but Obama riding a robot horse definitely pings the coolometer. I'm gonna have to go for the horse.