Best Looking Bitch(es). When walking into a party, it's obvious that this girl (or guy, I guess) is the best looking person there. It's a perfect acronym when referring to a hot person at a party or just place with lots of people if you don't know their name or want to be subtle with your conversation.
"We are going to be the BLBs of this party,"
"Damn, they are the BLBs here."