According to the Urban Dictionary it means either
1. Netspeak for baby
2. spanish slang word for "bebe"
3. stands for Bye Bye.
4. The abbreviation for Bitch Bully. Some may know this pharse as Double B.
5.A game in which at least 2 people (can be several) sit around each other. Speaking in regular conversation, or watching TV or any another activity, but if anybody says a word beginning with the letter B, they must say BB, or they receive a punch to the shoulder by another player, if they do not, they keep receiving punches.
But i doubt it means any of them
"A lot of football success is in the mind. You must believe you are the best and then make sure that you are. In my time at Liverpool we always said we had the best two teams on Merseyside, Liverpool and Liverpool Reserves."