In Florida, it is a criminal act to steal utility service, whether it is cable tv, electricity, etc.. I am not licensed in California and can not give advise regarding your state's law.
Even if it is not a crime, be aware that cable companies have technology that enable them to determine usage at a particular location, so re-locking the cable box will not prevent the cable company from learning of your activity.
With all due respect to your financial difficulties, you should consider an alternative for your entertainment, such as Netflix or Walmart where you can have an unlimited number of DVDs sent to you each month, and discontinue what you yourself appreciate is stealing.
Good luck in your decision making process, and getting back on your feet financially.
It is called theft of services. It is just like theft of goods, only what it is that you are taking is not tangible, like a TV set stolen from a store, but is an intangible, but still valuable, service.
Note that the cable companies generally are able to detect theft of service and they do prosecute. I've had several clients over the years who engaged in various manners of using cable services without paying and they were discovered and they were prosecuted. The cases go to federal court, not the local district courts. Statutory damages (the cable companies are not required, by law, to establish what it was that they actually lost, the damages are automatic) are generally 3 - 6 thousand dollars depending on the context of the alleged theft.
Based on my experiences, it will cost you far less to figure a way to validly pay for your cable, than it will cost you when they detect the unauthorized use and prosecute.
In the interest of full disclosure, I do not now nor have I ever represented a cable company, but I have seen bad results as described above.
This answer is provided for informational purposes only. Actual legal advice can only be provided in an office consultation by an attorney licensed in your jurisdiction, with experience in the area of law in which your concern lies.
Probably not the best idea. Theft of utility services, including cable TV falls under the general theft categories. If the value of the service is under $400, it can be a misdemeanor and over $400 it can be a felony.
Cable can add up and if you've got all the premium channels, it could add up quickly.
You're risking arrest and prosecution.