OP, I'd stop going to that particular location. Or, if that's not possible, next time he demands "Smile," tell him "No, I don't feel like it, and if you don't stop demanding it, I'm going to stop giving you my business." Or even, "You may think you're cheering someone up by telling them to smile, but not everyone wants to." Sometimes it's part of customer service demands; when I worked at certain chains, I had to keep up a bright smile no matter what as long as I was behind the counter. But if you are the customer, you don't have to perform "happy" on demand. Go somewhere else. And don't smile unless you darned well feel like it!
I'm not the first to say this on this forum, but I suggest the Sheldon Cooper smile for these situations.
I use this one myself:http://www.youtube.com/watch?v=M4FcHxDBel0
Good thread, I can totally relate to what the author is saying. I know others have had different experiences, but in my case it has always been a man telling me to smile. I've never heard this type of comment directed at a man.
I KNOW, RIGHT?! I've spouted off about this a lot, because this is one of my biggest peeves and I too have a "serious" face. And it's usually some guy, but sometimes an older woman, demanding "Smile!" The old guy who did that to me in the grocery store line got the version in my link. The one who demanded it after a family death got a "No." The elderly woman who insisted I needed to smile because I'd "look so much prettier/nicer [I don't remember exactly which it was] if you did!" got "Well, I'm functional, not decorative." But I do like the version with "Smile!" "Dance!"