I used to work in a grocery/g.m store as an overnight lead cashier. Which meant I was basically the person who got bitched out when something wasn't right.
One week we were having a sale (not too great a sale mind you) on boxes of snack cakes. We sold out though and this one guy wanted a rain check for it. I happily gave him one for a quantity of 12 (which is twice what I was obligated to give him).
He went batshit crazy. He wanted the ability to buy TWENTY FOUR boxes of these stupid snack cakes. I tried to explain to him that it was against policy, him getting twelve more boxes of cakes wasn't worth me potentially losing my job.
He went crazier and said, "Don't be such a fucking BITCH and give me the FUCKING RAIN CHECK. NOW." He spit at me too.
Finally, to get this dick out of my store, I printed off another receipt, crumpled it up and handed it to him. He left, bitching the whole way to his life partner about how I was such a stupid uneducated bitch.
At least the woman in line after him was nice. She saw the whole thing and calmed me down, telling me he was just being a whiny baby and stuff. Now THAT was a great customer. I ended up giving her $10 off her order and looking the other way about a policy.
Seriously though, is it worth it to spit at someone and berate them just because you were denied twelve ADDITIONAL boxes of cheap ass snack cakes?