I order a plain hamburger. No cheese. I mention that I have a serious dairy allergy, so really, seriously, no cheese. He smiles and nods and half an hour later the burger comes out--dripping with cheese. I sigh and grit my teeth, but this has happened before, mistakes happen, yadda yadda nothing to get upset over, and I send it back with very specific instructions this time: "I have a potentially fatal dairy allergy, and if I eat a hamburger with even the tiniest remnants of cheese on it I could die. Plz to be making a whole new burger, because even if you scrape the cheese off of this one it's been cross-contaminated with dairy, and I will still have a reaction if I eat it. New burger. No cheese. Kthx." Only more polite, because really, honestly, I'm nicer in person than I come across on the internet. Smile, nod, and two minutes later he emerges with a plain hamburger. "Well," he says, beaming, "the cheese came off cleanly, so here's your burger."
"Wait. Is this the same hamburger?"
"Yep, they got it off pretty easily, so--"
You jackass. I can understand getting mixed up the first time and telling the kitchen to make a cheeseburger by mistake, but after that? Were you listening to a single word I said? If you hadn't given me your "the cheese came off cleanly" crap, you know what would have happened? I would have assumed the food was clean, eaten it, and gone into anaphylactic shock right at the table. This isn't me being a finicky eater, this is me wanting to avoid a trip to the frickin' emergency room. And really, how hard is it to get a plain hamburger? I'm not asking you to bake me up a special non-dairy bun, I'm not asking you to miraculously produce some soy cheese, I'm asking for plain food. This isn't rocket science, pal.
I explain one more time, and half an hour later my food finally comes. It's delicious and does not set off any allergic reactions. The waiter, meanwhile, proceeds to ignore our table for the rest of the night. He keeps walking by, not even glancing at us, doesn't come by to ask how the food is, doesn't ask if we want our check or a dessert menu; I sit there for fifteen minutes with an empty glass as he keeps walking by, and eventually flag down someone else to get my drink refilled; when we're done we try five times to get his attention, fail, and finally have to literally grab his sleeve and ask for the check. If the restaurant had been terrifically busy, it would have been understandable, but it was practically empty and he kept passing our table. What a punk.
Edit: Yes, I did end up talking to the manager about the allergy issue. He was very nice about the whole thing, and judging by his expression when he went back to the kitchen to "have a few words with" the waiter and the cook, he wasn't too happy about what happened. Actually, I think that's what might have set off the ignoring, heh. Hopefully the waiter will get fired.