There's a sliding scale for this sort of thing
For instance: I would happily drink 4 cups (which sounds to me like approx 1litre ... I really dislike 'cup' measurements) of whole milk every morning
Agreed, I think cup is irrelevant outside of US - UK - AUS. Here it's just like saying drink "4 glasses of milk" - how much is this exactly? As usual it's a bit obnoxious to think your only customers / users come from those countries.
Off topic for the thread but seeing as you highlighted it: isn't 'liter' the US spelling, while 'litre' is the (correct) UK one? (I'm in Ireland, and tend to cringe when I see 'Americanisms' :( )
Just because it's "litre" in the UK and "liter" in the US doesn't make one correct and one incorrect. The latter is the correct spelling in American English.
It shouldn't, but it gets to be a lot of milk. Most people (that aren't dairy sensitive) could probably stomach a few more cups (8 fl oz.) without losing it, maybe up to 1/2 gallon. Throwing up usually happens when people try to drink a whole gallon in an hour type thing.
