Well because I care about getting answers for you people I googled it...LOL. Ya know a LOT of people want to know this. No clear answer but here are 3 possibilites...
- It evolved from the term "below job"
- It's blow from the receivers view...as in blow like a volcano
- It originated from those doing it to get money to buy cocaine aka Blow...but that just raises: why do they call it blow when you snort it so that's no help at all.
I'm afraid we'll really never know...makes me sad...confused...frustrated. Maybe a BJ would make me feel better?