Smokers should have respect for those who smoke and those who dont.
If your parents dont want you smoking in THEIR house, then you should respect that. Not try and make things to prevent them from finding out.
If you got caught with weed your parents could also get into trouble. It's not hard to go toke in your back yard or in the garage..
Im lucky, i live on my own so i aint gota worry about it :)