1. For crying out loud, stop that noise.
2. The teacher called him on the carpet.
3. I've got to get forty winks.
4. It has too many irons in the fire.
5. The storekeeper wanted cash on the barrelhead.

1.For God's sake, or: Fr heaven's sake, stop that noise. = Bring that noise to an end by all means.
3. I have to take a nap.

I can't help you out with no. 2, 4, and 5.
If I may assume though, no. 4 could mean that something is not safe; the risk of not getting something managed is higher than the possibility of getting it done. - But I'm not sureEmotion: wink
I couldn't find #3 or #5, but I've just found this in the dictinary:
to have several irons in the fire: to have various different interests, activities, or plans at the same time.

I didn't know that one!

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Right, Miriam - that's the correct meaning.
I wonder what I was thinking of - there's certainly a similar saying that fits with the explanation I gave [incorrectly] for no. 4.
When someone is "called on the carpet", they are about to be confronted about a wrong-doing by an authority figure, most commonly a teacher or a boss. The image this phrase brings to mind is of a person standing in the office of a teacher, principal or supervisor -- on the carpet, so to speak -- and being admonished.

"Cash on the barrelhead" is a term of purchase. It is the requirement for full payment in cash at the time goods are received. Other variants: cash on the barrel; funds on the barrel.
The phrase similar to 4. that Pemmican may have had in mind is: "Strike when the iron is hot." It means to take advantage of an opportunity before it's too late.

In blacksmithing, metal is heated until red- or white-hot and then worked with a hammer. Once it cools, it is no longer malleable and can't be worked.
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That's it - thanks, dave.
Forty winks . To have a rest . To sleep for a short time
Cash on the nail. Pay instantly.
Had him on the carpet. Reprimanded him.He has too many irons in the fire. He has too many interests.