Flatulence has been the butt of boyish humour for far too long, and while some people enthusiastically expel their emissions for a laugh, most people prefer to subdue the scent. CH4 (which is also the chemical formula for methane) straps to your belt or back pocket and claims to monitor your ‘output’, so you can work out which foods cause churns in your stomach. An accompanying app helps you keep track of your meals, negating the risk of accidentally eating a particularly reactive dish before jumping on an overseas flight.