My friend ordered an omelette without the eggs before, and it worked. A server wouldn't sell me a double shot of Jager because it was "too much alcohol" but had no problem selling me two single shots at once.
I've never had that problem. I basically always order milk anytime I eat out. Sometimes they only give me a kids portion or even a kids cup (it was extra funny when my wife ordered it for me and I was away from the table changing a diaper while visiting family), but usually I get a full glass of milk