I guess my point is that if you were unable to initially notice the difference in sizes, then maybe you also were unable to notice the fact that you had a 16oz glass and your colleagues had a 12 oz glass, which would make yours a pint and theirs not. Well, maybe not, but I don't know how inebriated you already were. (And before you say something about the waitress claiming it was Imperial -- that may well be their codeword for ``real pint'', so as not to appear to be screwing the rest of their customers.)

As to why certain bars would serve one size versus another, I suppose it's up to the individual owners. Smaller pints would tend to make more money, but the local Bennigan's advertises serving ``real pints'', so I suppose that there's some cachet in imperial pints, especially for those that pretend to be Irish or English inspired.

As to why one bar would serve two different sizes when none of you thought you had made any distinction I have no idea. Mistake?