Hmm, I havent heard this before but it's possible it has something to do with being greedy for other people's things? Or maybe not sharing. We sometimes say "Don't hog all the blankets" but that literally means share the blankets with someone when you're in bed. There could be a couple variations in the idiom you're meaning to say maybe and its been mistranslated. If you "pull the rug out from under someone" typically that means you take your support or help away from them suddenly without notice, which usually results in them "falling" or failing at whatever they were doing. Another alternative idiom could be "pulling the wool over someone's eyes" which means to lie to someone and get away with it.

I think it's worthwhile to note that English idioms are very often said incorrectly even by native speakers. Many people have a tendency to mix idioms as well, so my guess is whoever said the blanket one to you was thinking of something else!

It sounds literal to me.

Not really. But you (and we) are free to make up new usage whenever we like ... https://idioms.thefreedictionary.com/blanket https://www.niftyword.com/idioms-phrases/blanket/ I guess the intended meaning relates to someone taking more than their fair share of something, in a two person (at least I think that's the normal maximum number for a bed, at least here in the UK at the moment) context.

No, I don't think this is an idiom. To "pull the rug out from under someone" is an idiom, as is "to pull the wool over someone's eyes" (as Carmel mentioned). I've never heard any idiom about pulling a blanket, though.

Never heard of this one. Is it perhaps "Pull the wool over someone's eyes?" If you pulled the blanket from my side, it could mean you're taking too much of something that should be shared.