A cantonese slang which's used widely in Malaysia. Similar meaning to 'Owned', or can be used when you're speechless, or dumbfounded.
You're expecting to meet someone at 6am, somehow:
You: So we're gonna meet up at 6 aight?
Someone: what? since when!?
You: Cha dou -_-'''
Someone: you sound as if you're eating something really delicious
You: i AM eating!
someone: I'm very cha dou..
Afterall, these words are pretty hard to understand, you need to practise a lot and use them naturally :D