Generally speaking, stabbing people, larceny, treason, hijacking vehicles, assaulting policemen and shooting schoolchildren will get you either deported or jailed, or sometimes just a smack on the wrist and a sharp warning.

Break any Chinese law, even if the Chinese regularly do.

Selling drugs or being involved in political activism are two other big no-nos!

Drugs, assault on a Chinese Citizen, and driving without a license. These are the largest violations that I try and defend foreigners for. Truth is, money can buy you out of a lot of things. But expect to be deported. The deportation for drugs is permanent, assault is generally 60 to 90 day stamp that will not allow you to enter until after the expiration of the stamp. Driving without a license is the same. Drugs, depending on the amount and what it is, you're in big trouble even if you pay them off.
Small drug offenses Mary Jane in small quantities is 30 to 90 days in jail and deportation stamp depends on how much you've paid for them to be nice.
Large drug offenses including selling are punishable by death. Usually before that they'll give you 15 to 20 years in prison, enough time to live out your shortened life and then they will execute you.
Make no mistake, each provience and sometimes cities have their own set of laws. Drug trafficing is a mistake. I've known foreigners to thing that smoking a little Mary Jane is harmless considering it grows wild here in China. But on the otherside, I asked him why did he decide to take it to a bar. Should of kept it home, and most of the time, that makes you safer.
I know that some of you will say but the Chinese do it. Well, the thing is, you are twice as noticable than they are in public, and there are people who are jealous of us also, they wouldn't hesitate to give the local authorities a call