In Chinese, 666 stands for '六', which means fortune and luck. This is usually used to praise somebody, especially in game. You can also add more 6 to emphasize.
Wow you took over there towers! 666!
This new skin is so cool! 666666!
666 is the Devil's number. It is stuck between Myth and Legend because half and half of the people in the world are choosing the opposite. One thing that I can tell you is NEVER CALL 666!!! (CURIOSITY KILLS)
Me: Maybe I should call 666 because this definition says don't. I am just curious.
*telephone rings, other side of the line picks up*
Me: Hello?
*raspy breathing from other side of line*
Me: H-hello???
*screams from other side of line*
3:00 am
*you wake up*
Me: I heard a crashing noise?
*looks at door and door opens, creaking*
*a black creature flings itself onto you and eats you up*
Me: AHHHH!
Never call 666 kids!
In Chinese, the number six is a well-known number to praise people in having the job done well, or play a trick well. Six indicates the Chinese word "溜", as they are pronounced just the same. Generally, people would like to use several six to show their surprise and respect on your performance. Three six is one of the classic usages.