A product that came out last year overseas, now seems to have a domestic version, at a relatively cheap price of 35 RMB on Taobao.
You insert the coin into XX, and this method is really cool. Moreover, every time you insert a coin, it will release a fart. There are different kinds of farts - long ones, short ones, etc. Unfortunately, there are no silent farts. It would be even better if it could produce a smelly fart.