A troublesome customer (how it should have gone).

    I glanced up at the clock on the monitor. It was fifteen minutes into my break, and I still had filing to do behind the register before I could take off. My replacement had arrived on time, but the constant stream of customers had kept me pinned behind the desk. Now the line had dwindled to three people, two of them apparently a couple. I finished helping the customer in front of me, then turned to the other cashier.
    "My break started 15 minutes ago, so I'm going to take off now. Do you think you can handle this on your own?" She smiled and nodded at me. "Awesome. Where was that binder? I have a donation sticker."
    "Wait a minute," Interjected the next customer in line, an elderly woman standing with her husband, two slim volumes balanced upon her palms. "I have to wait now because she wants to take a break?" She turned to her husband, the look on her face self-righteous affront.
    "I'm sorry, but I've been here a long time..." I began.
    "She's been here a long time! As if I haven't!"  The customer in front of her seemed to be nearly finished with her business, but I called for backup anyway.
    "Look, I've called backup. Someone else should be here shortly. But I really can't help you, I need to go. And I think you need to calm down and be a little more considerate of others." I took down the donation binder that my coworker had indicated, and began recording the sale.
    "I'm the customer!" She was close to yelling now, and I was having difficulty maintaining a smile-- I'm sure it looked strained.
    "Yes? And?"
    "Your customer service is awful! I can't believe you treat people this way!" She turned back to her husband, who had taken to throwing sarcastic jibes at me between her outbursts. "Can you believe this? She must really not like this job!"
    The implied threat is what did it for me. I returned the binder to the shelf, and approached the register. My coworker was trying to mollify the irrate woman, telling her that I had called for backup.
    "Well, she didn't tell me that!" Was the customer's huffed response.
    "I see that I've been wrong," I said calmly. "I didn't realize how much more important your schedule was than mine. It's true that I'm rather behind on taking my medication, but since your time is so valuable I can put that off a little longer. Surely nothing bad will happen."
    "Well, finally!" The customer trounced over to the counter, angrily dumping her books in front of the scanner. I keyed my employee code into the register, then leaned across the counter to for her purchase. As soon as she was in range, I twitched the specialized muscle in the corner of my eye, causing the vessel there to burst.
    Jets of blood shot from my eyes, hitting the customer squarely in the face. She began screaming and stumbling backwards, flailing into other customers, who were backing away themselves. With a quick thumb's-up to my grinning coworker, I clutched my hands to my still-bleeding eyes and staggered out from behind the register. Headed up the escalator and towards the breakroom, I made sure to mutter "Oh gods, oh gods..." whenever a customer approached, for effect.
    Only three people stopped me to request directions, making it the most effective aversionary tactic I have yet devised.