It appears to have originated in Texas around 1967. It is a reference to the frenzied and hectic pace of New Yorkers' lives. A New Yorker does in an instant what a Texan would take a minute to do.
"I've been trying to, but you've lockblocked me like 5 times in a row now!"
2 a primary job; a day job
I'm an editor--primarily of technical documentation for my JOB job, but I also dabbling in things like web site authoring on the side.