Tea

[Koga No Goshi]

Oolong with sugar is not exotic, it's barbaric. Oolong should be served plain and hot.

Oh no no no no no no no no no.

You don't put sugar in Chinese teas. You might as well, seriously, put a pair of boxers over your head with "I'm a white westerner" written all over it if you do this near Asian people.

Other off-topic etiquette tips:

Don't leave your chopsticks standing upright in a bowl of rice. (Extreme bad luck)
Don't let Asians see you putting soy sauce on almost anything (unless they are doing it too) and prepare for stares if you put it on white rice.
Tap the table with your fingertips twice when your drink is refilled. (It's like "thank you")
Edit: Forgot one. Don't order coke or soda in Chinese/Japanese restaurants. No one has ever explicitly said anything rude about it but I can palpably feel the "ugh... okay" sentiment when people order this in Asian restaurants. ;)

/random.