blood blister

1. Literally, a blister that is filled with blood rather than serum. Be careful, I got a nasty blood blister after pinching myself with those pliers. How long does it take for a blood blister like this to heal? A: "Ouch! That was quite a pinch!" B: "Look out, you'll probably get a blood blister."

2. Sister. The term comes from rhyming slang in which "blister" rhymes with "sister." Primarily heard in UK. I've got two older brothers and a younger blood blister. A: "We have an extra ticket if you want to invite your blood blister." B: "Thanks, but she's actually doing something with our mom that night." As the only boy, it was pretty annoying to grow up in a house with three older blood blisters.