When a guy has brought a girl to his bedroom and has gotten all her clothes off but the panties. When he tries, she gives him last-minute resistance. They usually spoon or something afterwards.
Donny: Yo dude, so what happened with Vivian? Eh eh ?
Rudy: Not a whole lot.
Donny: Details, bro
Rudy: I got her in bed, but then she put on the panty-lock brakes. I'll have blue balls for a fucking week.