Battery operated fart sounds, works great, plenty loud, all the great parts of a fart explained and reenacted, as repetitively as your little finger can peck away, by aFarts: a spotter’s guide, fart jokes (Hardcover, 2008).
because everyone can always be more educated on a myriad of subjects, why not expand your personal experience and knowledge into the nuanced world of flatulance. (this is my fine word work, not ai, just fyi...)