Having had my formative years in New Zealand, I was born in South Africa. I vaguely recall when I was VERY young having someone tell me when I said "hey" that "hay is what horses eat".
I got that then it was more when people would yell "hey" across a room to attract attention, and that was considered a bit rude for that purpose.
However in my adult years in NZ and the UK, a casual nod and a "hey", or "hey, what's up?" was a perfectly acceptable greeting.
Having recently moved to Canada, I greeted someone casually with that yesterday to be told again "that's what horses eat". I felt a bit rebuffed, but decided to ignore it until I could research it – ie, ask on here!.
Is this just a North American thing? Or just possibly this individual's view? Same age and gender as me.
Best Answer
Pretty much the only time I remember hearing "Hay is for horses" intended as an actual admonition, as opposed to a lighthearted and humorous response, was in elementary school. I think our teachers used the phrase to remind us that "Hey, Mrs. Johnson" was an inapproriately informal way to get a teacher's attention – that we should try something like, "Excuse me, Mrs. Johnson" instead.
So many people heard that refrain growing up, though, that I've heard it get tossed out reflexively every now and then.
As for what message the person you greeted was trying to send, it's hard to say for certain. I think some people respond to "Hey" that way in an attempt to sound witty, while others may have misinterpreted our lesson from childhood to mean: using "hey" when addressing someone is always rude. In the former case, I don't think anything so trite ever comes off as very humorous; in the latter, it's professing ignorance for language, since the word isn't inherently rude, and isn't even spelled the same as its cow-feed homophone.
For the record, NOAD even lists "hello" among the word's definitions: