jack it up
You’re jacking off, but it's not because you're horny, it's because you're about to get laid and you're just trying to get your meat ready.
I jack off before I go to her house, just so I don’t look like a total failure.
He jacked off in the car on the way over, and now he’s got a boner for the entire date.
She jacked off in the bathroom before the interview, and now she's ready to seduce the boss.