slip a cog

Idioms  

1. Also,. Lose one's ability to reason soundly or make correct judgments, as in She must have slipped a cog or she would never have gone out barefoot in December, or What's the matter with him? Has he slipped his gears? These slangy usages allude to a mechanical failure owing to the cog of a gear or a gear failing to mesh. The first dates from about 1930, the variant from the 1960s.

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Example Sentences

See Examples For:

slip a cog

On the second round, he seemed to slip a cog on the par-three fifth hole.

From Time Magazine Archive

But Margaret-by-the-day proved an interesting game, if it did slip a cog or two in its development.

From The Girl Scouts at Sea Crest Or, the Wig Wag Rescue by Lilian Garis

"Yes, if they have had any warning or if our plans slip a cog anywhere we shall be repulsed to a certainty."

From Bucky O'Connor by William MacLeod Raine

They will go on prospering; there is no further reason why he should bend a wire, slip a cog, or delay the hurrying wheels.

From Floyd Grandon's Honor by Amanda Minnie Douglas

I will try to answer your questions, but you know after a lapse of forty years, one’s memory may slip a cog.

From History of 'Billy the Kid' by Chas. A. Siringo