my suggestion is you dont have to tell your parent that u smoke... but when u get caught, and i say when because it happens and unless your extremely careful you will get caught, so just tell your parents when they catch you. theres no point saying 'i was holding it for a buddy' and that kinda shit cuz all it does is make them want to catch you again and prove its you. so by just saying 'yeah its mine i smoke pot' or whatever keeps them off your back cuz your dont have to hide it anymore. and you never know, they might be ok with it