Is the word "repeat" really used as a synonym of "vomit"?
Solution 1:
One meaning of repeat (intransitive) is:
- (of food) to be tasted again after ingestion as the result of belching or slight regurgitation
- to belch
(The Free Dictionary)
I don't think it could be misunderstood over the phone. The teacher was probably joking.
Solution 2:
I have never heard the word "repeat" used in this manner. It definitely wouldn't be confused in American English. Might be a more common usage elsewhere.
Solution 3:
People sometimes say that a strongly-flavoured food has 'repeated on them', meaning that they have brought up wind from the stomach some time after eating and caught the flavour again. I suppose that's what the teacher was thinking of, but I wouldn't say that 'repeat' was a synonym for 'vomit' or would be misunderstood as such.
Solution 4:
So I am a native English speaker (well, New Zealand English, which is close enough :P) and I definitely use this in the sense given by the other answers (when I taste food again, usually something strongly flavoured or cucumbers). I wouldn't use it in the sense of to vomit, and I wouldn't misunderstand what was meant by "Please Repeat" in that context (actually I'm having a hard time thinking of any context where there could reasonably be confusion). In terms of my usage (not necessarily standard) the subject of repeat would be the food itself, and I'd usually follow it with "on me".
E.g.
"I don't like cucumbers, they tend to repeat on me."
"That curry I had last night is repeating on me."
Personally I would tend to prefer the usage "Please repeat that", but I don't think it is likely anyone would misunderstand "Please repeat".
Solution 5:
The following usage of repeat is definitely of common or semi-common usage in Australian English, based on experience. The word would not be used this way:
"I had a huge night out on Friday and spent most of Saturday morning repeating in the bathroom";
but might well be used this way:
"I stayed up until 3 after eating that kebab which kept repeating on me and wouldn't let me lie down".
It generally means a sort of unpleasant half regurgitation, somewhere north of a burp and south of a retch.
While it's amusing to think that the different usages could be confused here in Aus, I can't remember ever making such a confusion or having to explain myself in correcting somebody else's. (Though I'd be far more likely to use "say that again?" or just "say again?" than "please repeat" while speaking with a person...)