I've told this one before:

At a restaurant in Montreal a few years back, I was called names (in French that they assumed I didn't understand!) and actually shouted at for 'not' leaving a tip - my father doesn't believe in tipping beyond the 'rounding up' that is done in places in Europe, whereas my mother and I do "as in Rome" (and I live in Canada so hardly new to me) so when my father pays by card, either my mother or I discreetly (by prior ladies room visit to see who has what cash!) leave a 'correct' cash tip tucked under a water glass or similar (we even offer to 'check' the bill for my father as his sight isn't great to make sure we don't unintentionally stiff them!!)

In all my years, in all the world, never has a waiter shouted at us when the slip has read a low amount - a couple have asked whether the service was ok (and my mother and I have our routine down pat for that so everyone is happy, and usually involves distraction of my father while the other one explains our method to the server!) but this guy in Montreal was obnoxious and I made a point of picking the cash up off the table (he hadn't noticed that it was there under my water glass) and pointedly putting it in my purse while telling him why in (albeit poor!) French!