"Wángbādàn" is a practical slang that you have to remember. "Wángbādàn" means "bastard". When someone do something wrong to you, you can say this word to show your anger. However, you need to remember "Wángbādàn" is kind of offensive. Let's see an example.
Example:
Your friend: Damn! They forgot to put tapioca in my milk tea!
You: Those "Wángbādàn"!
Chinese Slang 101

Chinese Slang 101: "Nǎocán"
"Nǎocán" is a modern way to say "Báichī", which means idiot. "Nǎocán" is mostly used by young people. "Nǎocán" literally means "disabled brain" in Chinese. You can use "Nǎocán" when you see someone have done something really stupid.
Example:
Your friend: I keep losing wars in Clash of Clans!
You: You are really "Nǎocán"!
Example:
Your friend: I keep losing wars in Clash of Clans!
You: You are really "Nǎocán"!
Chinese Slang 101: "Gàn"
"Gàn" is pretty similar to "Cào". I personally feel that "Gàn" is probably more practical than "Cào" in daily conversation. "Gàn" means "fuck". People usually use "Gàn" when they are angry.
Example:
Your friend: Hey, I just accidentally broke your iPhone screen.
You: "Gàn"! You are in deep trouble!
Example:
Your friend: Hey, I just accidentally broke your iPhone screen.
You: "Gàn"! You are in deep trouble!
Chinese Slang 101: "Báichī"
This is an important bad word that you must know. "Báichī" means idiot in Chinese. When someone do something stupid, you can say this word to him/her. More importantly, when someone say "Báichī" to you, you need to understand the word and react quickly. I will show you in the following example.
Example:
Someone: You know, you are a "Báichī"!
You: You are a "Tāmāde""Báichī"!
Example:
Someone: You know, you are a "Báichī"!
You: You are a "Tāmāde""Báichī"!