We say Merry Christmas or Happy Christmas
say thanks, you too!
Joyeux Noël.
Feliz Navidad
Joyeux Nöel!
Scrooge initially replied with "Bah, humbug!" whenever someone said "Merry Christmas."
The link has a pretty complete list of how "Merry Christmas" is said in different parts of the world.
Frohe Weihnachten... merry Christmas
Russia.
Shub Krismas OR Krismas Ki Subhkamna
4 times because i counted it every time i said it.
China