Hello, young reindeer! To say "Merry Christmas" in Korean, you would say "Seollal Chukhahae" (설날 축하해). It's a traditional Korean greeting that is often used during the holiday season. The phrase "Seollal Chukhahae" translates to "Happy New Year" in English, but it's also commonly used to express well wishes for the holiday season. So if you're looking to wish your friends and family a happy and joyful Christmas in Korean, "Seollal Chukhahae" is the phrase to use!