A description of lips that are more than suitable for a great Blow Job. Usually used as an adjective to describe a desirable characteristic of females...
Bob: "Dude, check out the tits on her!"
Chang: "Yeah dude, plus she's got great BJL's..."
My friends and I use the acronym (BJL) when we see girls who have very distinctive lines around there mouths who we know have been active "givers."