Got swore at by an angry customer for calling them "mate". It was amazing.
Was doing overtime at the petrol station. One chap was having trouble and hadn't chosen his payment method so as usual had to go on the tannoy and break it down for them:
"Pump number X you just need to select your payment method mate above the keypad..." Nothing patronizing, just casual. Same way I've spoken to every customer in my lustrious retail career with no hitches.
Cue hand gestures along the lines of 'I've done that and it's not working, here's my car and here's the nozzle, see?'
Preparing for the whirlwind when he enters, however he sends what we believe to be his mail-order bride in to pay. Very anti-climax. But when driving off he turns near the hatch to which I am sitting next to, winds down his window and shouts something, I couldn't make it all out, but the general jist was "Don't call me mate, show some respect". I put my hand to my ears to show I couldn't hear him and we can see him call me a prick before he drives off.
Since I'm a Master at making people feel appreciated I got on the tannoy and said "Have a nice day." It put all the other customers in very good humour.