A question appeared on the Roman History Reading group on Facebook that you might enjoy, especially since I was able to help with the answer. Here's the question:

Does anyone have a source/citation for this quote/decree attributed to Claudius: "all Roman citizens shall be allowed to pass gas whenever necessary" (And why hasn't such a memorable quote shown up in a fiction book...?)

It appears in Suetonius' Life of Claudius (32).

Here is the relevant passage from an English translation:

XXXII. He gave entertainments as frequent as they were splendid, and generally when there was such ample room, that very often six hundred guests sat down together. At a feast he gave on the banks of the canal for draining the Fucine Lake, he narrowly escaped being drowned, the water at its discharge rushing out with such violence, that it overflowed the conduit. At supper he had always his own children, with those of several of the nobility, who, according to an ancient custom, sat at the feet of the couches. One of his guests having been suspected of purloining a golden cup, he invited him again the next day, but served him with a porcelain jug. It is said, too, that he intended to publish an edict, "allowing to all people the liberty of giving vent at table to any distension occasioned by flatulence," upon hearing of a person whose modesty, when under restraint, had nearly cost him his life.

 

The Lives of the Twelve Caesars, By C. Suetonius Tranquillus; The Translation of Alexander Thomson, M.D. revised and corrected by T.Forester, Esq., A.M.

The topos of Claudius' flatulence appears in an early work of fiction, the Apocolocyntosis, attributed to Seneca:

At once he bubbled up the ghost, and there was an end to that shadow of a life. He was listening to a troupe of comedians when he died, so you see I have reason to fear those gentry. The last words he was heard to speak in this world were these. When he had made a great noise with that end of him which talked easiest, he cried out, "Oh dear, oh dear! I think I have made a mess of myself." Whether he did or no, I cannot say, but certain it is he always did make a mess of everything.

Public Domain English translation by W.H.D. Rouse, 1920

Of Related Interest: Franny Syufy's Why Do Cats Fart?