"I've never heard of an advent calendar...is it Jewish?"
I'm pretty sure he or she was joking about the Jewish part. But he or she really had not heard of an Advent calendar before. I bought one after Christmas last year at Target that I had had my eye on all season. It looks like a house and has 25 little doors the perfect size for a treat. (Or two, as I told he or she that I would put one in for each of us.) When I was younger we had one that we tied peppermints to and ate one each day.
I love little things like this.