Hey,
Well first of all, if you even mention that 'under-the-table' job of yours, you wont have a job anymore. Your employer is breaking the following laws:
1. You're not paying taxes on the money you are earning. Which is against the law.
2. Your employer hired you illegally. You are working illegally.
Your employer can be fined, arrested or even just investigated. IF you take this to court, keep that job to yourself.