This happened many years ago, so there's nothing I can do about it now, but I wonder what, if anything, I should have said.
In my youth, I had a very large bust, even though I was fairly thin. It was very hard to find dresses to fit my bust. Most of the time, I had to buy a very large size, and then I'd be swimming in the waistline. I was asked to be a bridesmaid in my cousin's wedding and she just told me to pick any dress, as long as it was a specific color. I had a very hard time finding a dress, mostly because of my bust, but also because it wasn't a common color. I eventually found a dress that kind of fit and since I couldn't find any others, that's what I wore. It was the only one like it at the store, so there weren't other sizes to choose from.
At the rehearsal dinner, I was introduced to the father of the groom. Based on the small amount of chit-chat we made, he seemed nice.
For the wedding, my dress was a little large at the waist but was very tight at the bust. From behind, you could see wrinkles where it was tight. An observant person would have noticed that the wrinkles were at the bust line and not because I was overweight and trying to squeeze into a small dress.
At the wedding, the father of the groom came up to me and said "You should have bought a larger size. Your dress is tight."
I was so shocked. Who says that to someone? I wasn't about to lecture him on how it's hard to find dresses that aren't mumus that fit. I took the comment to mean "You are fat. You should not try to squeeze into things." I was tempted to go off on him and tell him that I was not fat, and I was unlucky enough to have a disproportionate body, and who the eHell was he to criticize my looks, and what the eHell did he know about dress shopping. But I was so shocked, and I knew I'd probably never see him again in my life, so I just gave him a puzzled look, said "what?" and walked away. And I didn't speak to him again for the remainder of the wedding weekend.