My family did not celebrate Christmas growing up. We had no tree, no decorations, no carols...
When people find this out, they show a kind of sympathy that makes me feel I had just told them I was beat up by girls in middle school.
When I was a kid though, I avoided telling anyone who didn't already know. Of course, this took a little imagination on my part every year when asked what I got for Christmas. I couldn't just say anything. It had to be believable. And if I named items that particular friend had already seen me with, the jig would be up. I often fell back on the old pair of jeans and a cassette tape (one year it was G'N'R, another it was Megadeth - all unrealistic as my ultra nosey and conservative parents would never have bought those tapes).
The big advantage to my childhood without Christmas is that every present is awesome, even when it sucks. It still feels new to have people get me anything at all. So even with the bad presents (of which I have received very few), I'm not faking the excitement. Horray Christmas!