A friend of mine asked her dad to "pick up a couple of pairs of suspenders" for her the next time he went to the shops.
He blushed furiously, said he wasn't sure what sort of size or style to get her, and rather desperately tried to suggest that perhaps she should ask her mum to do that sort of thing. Friend was baffled by his response, and "Oh just some plain black ones will do fine, and I'm pretty sure they're adjustable one-size-fits-all kind of things, aren't they?".
The mutual confusion was sorted out when both of them figured out that while she meant "elasticated braces for men, that hold up your trousers and go over your shoulders", he though she meant "lacy underthings for ladies that hold up your stockings".