Mine is people who justify spending a lot of money on themselves or their SO/family by saying, "Oh it's an early Christmas present" to themselves or someone else.
Example: My sister and her husband just bought smart phone for themselves a month early. She said it was an early Christmas present. Ugh.
My opinion is if it's a Christmas present WAIT UNTIL CHRISTMAS to use it, give it, whatever. And using the excuse of, "Well I got it for a great sale price" doesn't cut it. You can buy something for a wonderful price and still have the self control to WAIT A COUPLE WEEKS or so. To me it ruins the surprise and the magic of the day. The day of Christmas turns out to be opening presents that you may have "wanted" but couldn't, "live without".
Christmas honestly makes me happy :) the month of December is so magical to me. Sounds corny i know, but I love the feeling of closeness I have with my family and it bothers me when I hear people talking about GIFTS all the time! I mean, come on! I get a present for all my nieces and nephews and my CLOSE family but we don't go all out. I think it's the thought that counts! This year I went to my MIL's and got pictures of her and my FIL from when they were younger, and the ONLY picture of her and my hubby from the day he came home from the hospital and had them copied and framed because she is sick and unfortunately this may be her last christmas. I CANNOT wait for him to open them because I know he will know how much thought I put in to it! That's what matters to me. Not buying my nine year old nephew the iPhone he asked for.