| Idiom | Meaning | Example | 
| corny | 
obvious humor, unsophisticated humor
 | 
The farmer said his cows are moody today. Now that is corny!
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| cost a pretty penny | 
cost a lot of money, had a high price
 | 
Elvis bought a new pink Cadillac. I bet that cost a pretty penny.
 | 
| cost an arm and a leg | 
cost a lot of money, is very expensive
 | 
That fur jacket must have cost her an arm and a leg.
 | 
| cost you | 
require much money or emotional stress or time or energy
 | 
Caring for a child will cost you - cost you a lot. But it's worth  every minute, every tear.
 | 
| cotton-picking | 
thieving, doggone, flipping, ruddy
 | 
Get your cotton-pickin' fingers off that bike! Don't touch it!
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| cotton to that | 
believe in that, do that, relate to that
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City folks play cards on Sunday, but we don't cotton to that.
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| couch potato | 
a person who watches a lot of TV
 | 
If I watch four hours of TV every day, am I a couch potato?
 | 
| cough up | 
pay your share, pay a debt, pay up
 | 
Come on, Tony. Cough up. You haven't paid anything.
 | 
| could care less | 
(See couldn't care less)
 | 
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| couldn't believe my ears | 
(See can't believe my ears)
 | 
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