If you're in a bad mood because of something unrelated to parents (like hassles or problems at school or work, etc.) and you can't even look at them without blowing off a steam, then take time out and calm down to have a normal talk later. If your parents are the cause, use your time alone to work out exactly what you want to say. Go over your feelings a few times in your head and when mom asks what's wrong, you can tell her calmly how you feel.
When you're calm you'll score points. Tell your parents that you need some space to deal with things in your own way and that if you need help, you'll ask them. Understand them too, they get neurotic 24 hours a day worrying about you. As long as they know you're ok and not headed to jail or hung up on drugs, they should give you space. Patience is key...

If you get angry and decide to ignore parents it will only play against you. The problem with giving your parents the silent treatment is that you get them angry too. By making them