A "B" is a good friend or Homie that you always laugh with. It can be used in any setting but was originated on Grateful Dead tour in the early 90's. Can also be used to describe when you are very tired and worn out. It can also be described as indentifying someone that has the same name....such as "Where's Jasmin?"....which Jasmin? "Jazzy B"
"Im Tired B"......"Where are all the "B"'s at?"....."meet us after the show, all the "B's" will be there
b is short for bag, the verb. bag is used to mean that someone is going to hook up with someone else. so when someone is trying to bag someone else, as in they are flirting or starting to make moves, one would make his/her right hand into a b (thumb straight up, fingers curled behind curled pointer finger) behind the person who is trying to bag. in addition, someone could say "b" or type it on facebook, text it, etc.
Example 1: Jack goes over to Anna and says, "Nice shirt," in a flirty way.
Aaron goes behind Jack and puts up a b with his hand.
People laugh
Example 2: On facebook, Jamie writes "wish i could've seen you today :(" on Ryan's wall.
Adrian comments on the wallpost saying "b"