well, that was mildly amusing. OK, sometimes if I get a "merry christmas" I respond with "and a happy hanukah to you!" or something like that. just to be silly, because really, I celebrate both, and I accept that I'm going to be wished a merry christmas about a million times in the next month. people who get their panties in a twist about it are silly...I think if you're working in a shop, "happy holidays" is best/most inclusive, because hey, there might be a holiday today you don't know about, and wouldn't it be nice if that were covered as well? but if it's a christmas tree shop, or a judaica store, or anything else specific like that, a little specific holday greeting is nearly always appropriate.