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Fart Whistle by Stocking Fillers
Not a very sophisticated fart noise but all is not lost. In conjunction with a clean handkerchief and a pot of green slime (available in most joke shops and probably Amazon) you can get yourself thrown out of restaurants, libraries, pubs, churches etc instantly. When blown into the handkerchief under the pretence of blowing your nose the device gives a very plausible and loud sound. Preloading the handkerchief with the contents of the slime pot and allowing it to fall whilst blowing completes the effect. Enjoy