I have picked up two idioms recently. These are: 'over a barrel' and 'not a barrel of laughs'. But I don't know how they work. I made up a sentence for each of them. Here they are:

-It was not a barrel of laughs.
-He got so annoyed when she had him over a barrel.

Are these sentences correct?
Here are some definitions:

Barrel of Laughs
If someone's a barrel of laughs, they are always joking and you find them funny.

Over a Barrel
If someone has you over a barrel, they have you in a position where you have no choice but to accept what they want.

Since the idiom is said to refer to a person rather than an object or a situation, I would change It was not a barrel of laughs to He was not a barrel of laughs, for example.

I suppose the second one is correct when put in context.
Yes, that definition is OK too, Red.

'Trying to fight through the crowds in Tokyo Station is no barrel of laughs.'
'Getting sprayed by a skunk is no barrel of laughs' (I think 'no barrel' may be more common than 'not a barrel')
'When my girlfriend got pregnant, she had me over a barrel-- I had to marry her!'
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My dictionary says:
not a barrel of laughs - informal - a very unpleasant experience or situation
Sadly, it doesn't give any examples for these two idioms.

Thank you
 Mister Micawber's reply was promoted to an answer.
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Your sentences were of great help to me. Thanks a lot.