Working at McDonalds last year (it's a sad life, but the money is there) I completed a big family order in like... 2 minutes. The dude was pretty happy with the whole thing and asked for some ketchup. We had literally just run out on front counter, and told the guy we had some round the side on dispenser. His expression suddenly changes and says "but we need the little packaged ones for the car". I suddenly think "oh crap, it's about to kick off" and say "I'm sorry, we're not allowed to leave the front area during an order, even to restock". As expected, the guy kicks off, giving me full verbal abuse for something close to half an hour. This is for something we give away as a COURTESY.
At the end of his rant, another customer (who I might add not even wanting ketchup) pipes up "yeah, we should probably get food trading standards involved". At this point I'd had enough, I'm a fairly big guy and this guy and despite my incredible ability to hold my nerve, I let loose "excuse me kindly SIR, but ketchup is available round the side. We give away cartons as a COURTESY, but it's been a busy day today and lots of people have taken them, just like you wished to. Just to point out, by now your food is stone cold and no, I'm not going to replace it. Have a nice day."
The guy, realising his MASSIVE error, suddenly looks mortified and his wife is standing there like "you're such an ass". Everyone on front counter absolutely pissed themselves when they left. I took the opportunity to restock ketchup
