"Barnes," Loki said. "Please."
What got to Bucky wasn't the circles Loki'd been leading him in all day--not letting him get off or even slow down enough to do anything else, so that things were way beyond uncomfortable by now. You had to be prepared for that kind of shit with Loki.
No, what got to him was how much Loki had to want it to ask. Sure, he fucked with people sometimes, but begging wasn't exactly one of his party tricks.
"So, uh," Bucky said, undoing his belt. "How exactly did you want to get pissed on, again?"