Today I heard my friend talk about last night, at a party, how he was hitting on this one girl over by the bar. In my own hung over head, I was thinking, ‘did he say he just socked a girl over by the bar?’
Of course this means complimenting another, usually with a sexual motive. But where did this odd phrase originate?
To “pay unsolicited and usually unwanted sexual attention to” (dictionary definition) or to “approach or engage with the hope of picking up” (how I would put it) is a long way from “find by chance.” Drifted? Heck, it’s not even in the same body of water.
Through regular use, the phrase (in that context) drifted from referring to the finding of the desired person, to the action that usually accompanies finding the person. This is a common idiomatic drift – people use words or cliches until they separate from their original meaning and develop their own meaning through usage. Look at “dude,” which has drifted from being a (mostly derisive) word for a man who is overly-concerned with having fine clothes. In its recent usage, it has absolutely no attachment to clothes – but by virtue of the people it was applied to, it’s come to be associated with other shared traits of idle youth, and lost its overtone of censure. It’s drifted. You can’t say that there must be a different etymology for “dude,” because these days it’s usually applied to people who dress like bums and don’t care.
As for “hit on”, it seems like a rather obvious evolution of an preexisting phrase to me, but I’d be interested to hear any other ideas as to how a phrase in common usage might independently spring up with this specific connotation.