An example of this is the term groovy which is a relic of 1960's and 70's American hippy slang. Nevertheless, for a slang term to become a slang term, people must use it, at some point in time, as a way to flout standard language.
Cycling is a highly effective form of exercise. It requires a lot of energy, builds lean muscle mass, and improves your strength, cardio capacity and endurance. However, cycling won't specifically burn belly fat. It will certainly help to reduce your overall body fat, but since spot reduction is a myth, you will have to be patient for your belly fat to burn off with the rest of your fat.
Bicycling combined with a good diet will help you lose both belly and thigh fat. I think it burns something like 700+ calories / hour depending on just how hard you push yourself. Swimming is another really efficient excercise.