When customers start aggravating me, I don't want to do **** for them... and I kind of stretch the truth about things that we appear to have run out of (but really, we probably have in the back). No spoons for your yogurt? Ah darn! All we've got are forks! They always think I'm kidding... but I'm not.
Also, the way my store is set up, customers sometimes encroach in our space... our little swinging doors are sometimes open and they'll be standing right next to me, inching their way in, watching, waiting for their drink. Breathing down my **** neck. This bothers the **** out of me. I do two things. First, I very dramatically close the doors on them and stare them down. Second, once I finish their drink, while they are standing beside me, waiting for me to hand it over to them... I will call it out in the opposite direction, and put it out of reach on the handoff, so they have to walk around to grab it. I try to be as much of a jerk about it as possible. :)