| Idiom | Meaning | Example | 
| for the life of me | 
it is a mystery to me, why in the world
 | 
For the life of me, I don't know why she stays with him.
 | 
| force of habit | 
from habit, because of a habit
 | 
She still cooks enough food for five people. It's force of habit.
 | 
| foregone conclusion | 
(See a foregone conclusion)
 | 
 | 
| forever and a day | 
for a long time, for an eternity
 | 
This treaty will last forever -  forever and a day.
 | 
| forget it | 
do not continue, stop it, I do not want it, drop it
 | 
I'm not interested in joining the club. Forget it.
 | 
| forget your manners | 
forget to be polite,  forget to say please etc.
 | 
When I reached in front of Mac, he said, "Forget your manners?"
 | 
| fork over | 
pay, pay up
 | 
They said, "Fork over, man. Pay your share of the bill."
 | 
| found money | 
money found on the street, money saved by nature
 | 
Wind power is like found money. I save what I paid for electricity.
 | 
| found out | 
discovered,  caught
 | 
If you cheat on the exam, you'll be found out. They'll see you.
 | 
| four-letter words | 
bad words, profanity: damn, hell, shit etc. [B]
 | 
He gave a good speech, but he used a lot of four-letter words.
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