It’s a harmless enough hobby. I collect flights of rhetoric that suddenly crash. They exert the same fascination for me that toy train wrecks do for little boys.

My current favorite is a gem from Paul Krugman, the verbicidal columnist of the New York Times, who writes like the economist he is. Warning against the Bush tax cuts, he prophesied: “And when the chickens that didn’t hatch come home to roost, we will rue the day when, misled by sloppy accounting and rosy scenarios, we gave away the national nest egg.”

Try to picture it. I can’t. Not without laughing. (That was George Orwell’s acid test for all metaphors: Picture them before using. It is a useful caveat for any writer to keep in mind.)

My old friend Father John O’Donnell has sent me a batch of similar sentences, all collected in one article by a connoisseur of the art, Francis Griffith. The genre turns out to have a name: Irish bulls. This herd arrived in time for last Saint Patrick’s Day, and I’ve been laughing ever since.

An Irish bull, I learned, is not a branch of the Hereford family. It is “a verbal blunder which seems to make sense but after a moment’s reflection is seen to be wildly illogical.”

The genre is supposed to have been inspired by one Sir Boyle Roche, a member of the 18th-century Irish parliament who was given to earnest inanities. For example, there was his response to another member’s appeal for some measure because it would benefit posterity. “Why, Mr. Speaker, should we do anything for posterity?” Sir Boyle asked. “What has posterity done for us?”

Sir Boyle was a dual patriot, deeply attached to both England and Ireland. Indeed, he wanted “the two sisters to embrace like one brother.” But he feared that Irish grievances would never be addressed. Or as he put it: “So long as Ireland is silent on this question, England will be deaf to our entreaties.”

This master of the Irish bull was moved to tears by Ireland’s troubles. “The country is overflowing with absentee landlords,” he complained, and, what’s more, “The cup of Ireland’s misfortunes has been overflowing for centuries, and is not full yet.”

It’s not easy to distinguish between an Irish bull and a metaphor that’s been run through a Mixmaster. Consider this poetic passage from one of Sir Boyle’s orations: “All along the untrodden path of the future, I can see the footprints of an unseen hand.”

Irish bulls are certainly not limited to the Irish, though the Irish may have a special talent for them. Mayor Richard Daley the First of the grand city of Chicago, where the river still runs green every St. Patrick’s Day, produced Irish bulls in profusion, the way he did dead voters every election day.

During the Democrats’ riotous convention in Chicago back in 1968, he assured the press that the police weren’t there to create disorder, they were there to preserve disorder! Which cleared that up.

To be really satisfying, an Irish bull must offer more than low comedy; it must have an air of pretension and sophistication, as in Paul Krugman’s contribution to my collection. For example, it’s hard to beat a classic formulation by Clarence Manion, a law school dean and minor ideologue in the 1950s who earned a place among the immortals with this towering piece of bloviation:

“There is every reason to believe that Republican forms of government, every branch of which is constitutionally committed to the protection of unalienable individual rights, could and would permanently solve the political aches and pains of the whole world. But there, as here and everywhere, mere form without substance must collapse of its own weight.”

But if you like your Irish bulls short and snappy, consider the collected works of the late great Sam Goldwyn, who infamously observed that a verbal contract wasn’t worth the paper it was printed on.

The Hollywood mogul could scarcely open his mouth without putting his foot in it. Among his finer productions: “Anybody who goes to a psychiatrist should have his head examined,” and “I’m living beyond my means, but I can afford it.”

Tastes vary, and some will prefer Yogi Berra’s (convoluted) way with words. As in: “Nobody goes there any more. It’s too crowded.”

The genuine Irish bull, says Francis Griffith, must be unintentional, spoken rather than written, and not be altogether absurd. It must be an accident of language, not mere gibberish.

The great charm of any Yogi Berra-ism is that we all know what the speaker meant. As when Al Gore, in his otherwise undistinguished — and unending — presidential campaign of 2000, attacked his opponent’s record by warning that “a zebra cannot change its spots.”

I could go on forever but, to commit a final Irish Bull, I think I’ll just commence right here.