Your parents are narc bags. I'm sorry had to get that out of my system first... lol. If you had a mini-fridge in your room you could save your piss that would be clean in your fridge and then when it comes to test time just warm it up some how and put it in the cup. As far as stashes go, you could put them in your geometry kit.

Like penguin said before me, you should have a talk with your parents about dope and tell them that it's not going to kill you or make you unmotivated. I can't believe the bull shit they put in these anti-drug ads, it makes me sick.