Xander kept a drawer of one filing cabinet filled for just this purpose. He was at his desk, trying to work. Spike was sitting in a chair on the opposite side of his desk, waiting for Xander to get done. Xander knew it was really "waiting for Xander to decide Spike is more important than work" but Xander really *did* have responsibilities and actual work and he even enjoyed his job and liked spending time on it.
Not anything like 40 hours a week, but that was what well-paid assistants were for.
But at this very moment he was doing some real, actual work, and Spike had snuck into his office *again*, despite every "vampires go home" spell he'd laid on his inner and outer offices.
Hence, the drawer. Spike was rummaging in it even now, and Xander glanced up to see his glurbleglurble grab a small box with an insanely gleeful expression. Xander looked closer -- of course. Paperclips.
Xander tried not to put paperclips in the drawer, but they got in there with the same inexplicable tenacity that Spike got into Xander's office when he really did have actual work he had to get done by the end of the day, and I mean it this time Spike. He supposed it was because he wasn't the only one who put random office-flotsam in the drawer. Several of his top execs, and their secretaries, knew about the Spike Drawer and helped Xander keep it full of things for Spike to play with when he was waiting for Xander.
He'd tried telling them, at monthly staff meetings, not to include paperclips. But he suspected that most of the rest of the building had some kind of bet going, on what Spike would manage to create-destroy-lose-summon-have sex with the next time, if he just had enough paperclips in the right sizes.
Even now, Spike was plopping down on the floor with a handful of boxes, and had started opening them. He kept them neatly in their respective boxes, instead of dumping them out -- as Xander would have guessed, back before he'd come to learn just how complicated and weird his glurble's brain was.
Grateful that he'd finally got his building insurance to agree to cover "things Spike does," Xander ignored him and got back to work.
Xander's insurance premiums included all-expenses paid vacations to the dimension of the insurance company president's choice. But Xander figured it was worth it. After seeing what Spike had done to the parking garage with a mere four thousand boxes of paperclips, the insurance company president had agreed.