misheard underwear made of fish, seaweed, crustaceans, etc.
Origins: Whilst at the pub on Saturday, the ever-shy-and-polite Steve mentioned to Kylie (who was wearing a shortish skirt) that her undies were visible in her current seated position. She immediately rectified the situation, commenting that she should be more careful, as she was wearing "see-through pants". Steve and I both misheard her, thinking she said "seafood pants". As is so often the case, the misheard phrase was far preferable to the actual one, causing a good ten minutes' worth of mirth and insinuations of venereal disease.
"Did you hear? Apparently Miriam has crabs"
"Serves her right. That's what you get for wearing seafood pants".