Well, I've had a few. One was last Valentine's Day at a neighbourhood Italian restaurant that made us feel completely unwelcome because, I guess, we weren't one of their "regulars." They gave us a lousy table and when we requested another one the owner got nasty and basically told us to like it or lump it. Moments later some regulars came in and were given the table we wanted even though we had a reservation and they didn't. I wanted to leave but my husband was right -- everywhere else was full. The food, wine and service were expensive and mediocre, and needless to say, we've never been back and have badmouthed it to everyone we know.
Then there was the time years ago when I was dining with colleagues at the Four Seasons in Beverly Hills. We were all a little over-refreshed and dinner took a long time to arrive. I was cutting into my lamb chops a little too enthusiastically and one flew off my plate and hit Steve Martin, who was dining nearby, in the head. Hard.
I was mortified. I went over to apologize in person and he was great about it and thought it was funny. When I couldn't stop apologizing, he laughed harder. He then sent our table more drinks, which was just what we didn't need but drank anyway to be polite. And all that apologizing had made me thirsty!