Unfiltered Story #229520

I am working the front counter at a well known Canadian coffe store. A gentleman comes in and orders a medium coffee. I make it for him, and he takes it and leaves. A few minutes later, he comes storming back in and slams the cup down on the counter in front of me.
Man: I ordered a medium and this is not a medium!
Me: That is a medium sir.
Man: No! No it is not! This is a small!
Me: Sir, that is a medium.
(I pull out a small, a medium, and a large cup to show him the difference)
Man: No! No! This is a SMALL. This is a small!! There’s an S on the lid!!
Me: It’s actually an S slash M because those lids fit both small and medium cups.
The man grabs his coffee back and storms back out of the store muttering the whole way about how he ordered a medium not a small.