Replying to Don't go to Burger King!

Me and my friends went through the drive through and the cashier gave me the wrong amount of change so I was like " Are you mentally retarded? You were supposed to give me $4.50, not $4.45!"
and he was like "oh, sorry!". Instead of saying like "Sorry, I'll get you a free burger". I was fucken pissed, he tryed to give 5 cents less. The worst part is when he went to get our burgers, we watched him spit in all 4 burgers. I went and told the manager and he checked the burgers. He fired the casher that night. Sick huh?