In J. D. Salinger's The Catcher in the Rye, Holden uses the euphemism "give her the time" to refer to Stradlater having sex with someone:
Stradlater kept taking these shadow punches down at my shoulder. He had his toothbrush in his hand, and he put it in his mouth. "What'd you do?" I said. "Give her the time in Ed Banky's goddam car?" My voice was shaking something awful.
"What a thing to say. Want me to wash your mouth out with soap?"
"That's a professional secret, buddy."
The Catcher in the Rye, chapter 6
I'm not familiar with this euphemism - the only place I've encountered it so far is in The Catcher in the Rye. And Holden - and the author - don't shy away from being more explicit:
Most guys at Pencey just talked about having sexual intercourse with girls all the time—like Ackley, for instance—but old Stradlater really did it. I was personally acquainted with at least two girls he gave the time to. That's the truth.
The Catcher in the Rye, chapter 7
Here, he uses both the explicit phrasing and the euphemism at the same time.
Where does this euphemism come from, and why does Holden use this instead of something else? What does this tell us about Holden?