How do you say happy father's day in Korean?

Happy Father's Day in Korean is "아버지의 날 축하합니다" (Abeoji-ui nal chukhahamnida). You can also simply say "아버지, 행복한 날 되세요!" (Abeoji, haengbokan nal doeseyo!), which translates to "Dad, have a happy day!"