For me, it may be that the toilet paper roll needs to have the open end away from the wall. I don’t want to reach under the roll to take a piece! That’s ludicrous!
That or my recent addiction to correcting people when they use “less” when they should use “fewer”
It gets weirder because you can also say “a pair”. And it gets even weirder because “a pair” means “2 that are meant to be together” whereas “a couple” means two that were put together, which is why it sounds weird to say you got a “couple of socks” (most people would understand this as 4 socks) instead of a “pair of socks”.
I’d understand it as two mismatched socks.