IT was one of those silly conversations that went off at a tangent. Like they do.

"He was as mad as a bicycle," Nick said.

Which caused the rest of us to stare at him in confusion.

"As mad as a bicycle?" I said. "Where did you get that from?"

"I thought everybody used it," said Nick.

Nick had lived in France for many years, so maybe something got lost in translation.

"Mad as a hatter, yes," I said.

The derivation of which comes from when mercury was used in the making of hats and unfortunate hat makers went mad.

"Or daft as a brush," said Ian.

Everybody remembers Bobby Robson’s affectionate quote about Paul Gascoigne, but where does the saying come from?

Well, it could be from the days when children swept chimneys. Young trainees often banged their heads, sometimes causing cerebral damage. Hence: daft as a brush.

The things you learn in this column.

"All right," said Nick. "Where does drunk as a skunk come from? Do skunks drink?"

Obviously not, but they can give off a pernicious aroma, as can someone who is extremely drunk.

Anyway, that’s an Americanism so doesn’t count.

But others were thrown into the arena of public debate.

Elephants, meaning drunk, was acceptable as rhyming slang: elephants trunk.

Drunk as a lord comes from the days when aristocrats would attempt to drink one another under the table, so not much has changed there, then.

And what about the real McCoy, meaning the real thing?

Who was the real McCoy?

It seems to come from the Edinburgh firm of Mackay who have made whisky since 1856. Their brand was promoted as "the real Mackay".

The pretenders come from America at later dates and seem to be derivative.

Such as Bill McCoy, a rum-runner during Prohibition, who brought the real stuff from Canada.

It has even been suggested that McCoy is a corruption of Macao, which was the source of a pure class of heroin.

The one alternative that I like best, concerns American boxing champion Kid McCoy.

A drunk challenged him to prove he was not an imposter. The boxer obliged by flattening him and the drunk slowly sat up on the floor and said, "Yes, that’s the real McCoy."

But wait, what’s this?

Could Nick have been right after all?

A Google search revealed that "mad as a bicycle" was used in Blackadder when Edmund, Baldrick and the delightfully daft George were discussing how the First World War started.

George said, "The war started because of the vile Hun and his villainous empire building."

Edmund Blackadder patiently explained, "George, the British Empire at present covers a quarter of the globe, while the German Empire consists of a small sausage factory in Tanganyika.

"I hardly think that we can be entirely absolved of blame on the imperialistic front."

To which George replied, "Oh, no, sir, absolutely not," while adding, in an aside to Baldrick, "Mad as a bicycle!"

Baldrick, of course, had the last word: "I heard that it started when a bloke called Archie Duke shot an ostrich ’cause he was hungry."

Edmund said, "I think you mean it started when the Archduke of Austro-Hungary got shot."

"Nah," said Baldrick. "There was definitely an ostrich involved, sir."