Yule hates Christmas. He hates any time of year when you are supposed to be joyous and happy for no other reason than it's a specific day on the calendar. (I secretly think Yule's an atheist but he hasn't told me that personally.) It looks like poor Mal has been emotionally scarred by what he read.
A bit of education for today: Yule is wearing a shirt with a "rebus" on it. A rebus is a little puzzle where pictures make up words or parts of words. (
http://en.wikipedia.org/wiki/Rebus) So his shirt reads "I hate Christmas". A friend of mine, Melissa F., loves these little puzzles and makes them with rubber stamps. I thought the idea cute for shirts, signs, and so forth in the comic strip.