Question about weed drug testing?

alright so i might have to take a hair or a pee test soon becuase my parrents know i smoke weed. im 16 and i like to smoke a little ganja every now and then. i have really short hair and i was wondering if i keep my hair short (under one inch) am i clear? i dont think you can test hair unless its over 1.5 inches? because i could definitly keep it short. also if i have a piss test does anyone know a really good way to fake it? im not going to buy any detox drink because i dont know when i would have to take the test. just wondering if anyone knows a easy way to pass.