Try to bluff

"Well, what the hell are you doing here?" growls the security guard, as he reaches
for his taser.

"Umm, I was sent by sent by maintenance to go and clean ... stuff, in the
lobby. Yea ... that's it," you reply.

"Oh, is that so?" says the security guard, his fingers hovering over his taser.
"If that's the case, then why don't you have any kind of cleaning equipment?"

"Well, umm ... maintenance always seems to find fit to never give me any
cleaning materials. They say it's out of budget, but ... Um, I think they're just
always trying to get a laugh out of me?" you reply, lamely.