Everything. I hate every second of every minute of every hour of every day of every week of the month of hell called the holiday season with a white-hot passion. I hate the crowds, the stress, the traffic, the incessant music (stations playing it since mid-November...and it's the SAME TEN SONGS!), and the assorted hassles. I hate the gifts I get (that I do not want and have no use for), despite repeated and increasinly-emphatic statements that I want nothing.
This year is the ultimatum: anything addressed to me will be burned unopened.
You aren't nearly nasty enough. I can reduce a Christmas dinner party to tears in less than 15 minutes. Today with the myriad of choices it is entirely possible to sail through the entire holiday season with nary a sprig of mistleto.
Simply return gifts with the following note:
This would better decorate your garbage can than mine.
That will be the last you get. I can give lessons in being obnoxious.
If the gift is from a spouse, hand it back saying "you throw it out and cut out the middleman. I should not have to throw it away when you should do it.