I became such a valuable member at one retail job that I could be a total bastard to some customers. It was great. I love smurfing people like that over.
At a different job, I had a guy threaten to beat up the staff then, when a customer asked him to calm down, threaten to beat up the other customer too. I threw him out and told him to smurf off. While he was in the store, he kept going on about how he owned three hair salons in Oldham, as if it somehow entitled him to act like a :bou::bou::bou::bou:. It's always nice telling those "the customer is always right!" sorts to shut the hell up or get out.