tell them what you think, tell em what you believe, get your facts straight first- NORML is a good place (i use Norml.org.nz whenever i need some facts)

"Im not going to stop simply because you disaproove, i dont think there is anything wrong with my marijuana use. Cannabis is a completely safe, non-toxic, gentle herb which gives my mind a safer high than alcohol- which you drink. Im not embarrassed, im sorry you dont agree, but i will continue using marijuana for recreational, relaxation, religious, and medicinal purposes."

or whatever..

It is illegal, but make them see the illegality is not the issue because it should not be illegal, because it is NOT BAD at all.

tell em youll never stop, DEFY the drug tests..

on the other hand, dont piss off youre parents, and it depends how old you are..