All you can eat.
"The word "good" has many meanings. For example, if a man were to shoot his grandmother at a range of five hundred yards, I should call him a good shot, but not necessarily a good man." - Gilbert K. Chesterton
So... what? Good that she's living life.
If you found a note between her and her friends explaining their plans to drop their crate of injectable heroin & orange juice off to their pimp to pay off debts for their HIV cocktails acquired in the process of servicing your local community's night clubs ... OK. Maybe you could fuss and post on the MMOC forums about it.
But seriously. This. I think the older:baby relationship is inverted here, tbh.
I hate "non-drug-users-trying-to-fix-your-life-because-when-you-once-take-drugs-you're-an-junkie"-types.
Stop beeing that guy, even if it's your sister.
I occasionally take drugs ( Acid, Ecstasy ) with some of my best bros. Everyone has job and we're very social ( obvious huh? ).
We're taking it only on big event's so in two months perhaps once to 2 times. None of us are addicted. ( in b4 You are addicted because you deny it that you're addicted )
Also it seems that it's just weed. Just look that she doesn't get like those gangsta-kiddys trying to be cool with weed. Weed sucks.
If it's a "harder" drug tell her to drink much ( water, non alcoholic stuff ) and get her clean stuff. If she's interested she's going to try it anyways, if you're going to forbid it, she wants it even more. So option 1. Clean Stuff, no dehydration 2. racked shit, dehydration, bad trip
Tell her she should do a little research on the drugs she's going to use and ( if possible ) to have someone to be there who was already on it, and stays clean to look after her.
Protip: not everyone who uses drugs ends up as a heroin addict dead on a public toilet ( Well the heroin addicts excluded lol )
"Blood Elves also have grapefruit juice for blood and a Blood Elf corpse left on the battlefield long enough will hatch into a lizard; chest-burster style."
I just don't see where you're arguing from... was it some childhood event that caused a couple bolts to come loose? You attempt to make claims that are ridiculous and majority of your attempts to outwit me are with derogatory insults that mean little to nothing other than the fact that you're showing signs you can't continue to argue in topics you have no insight in.
In the short term of smoking a little bit of weed one evening it doesn't sound so bad, but anyone that has smoked weed knows it can easily lead to other things. If it becomes habitual it can have an effect on your surroundings. The people you spend time with, new friends and opportunities you're presented with.
OP: if you're concerned and you obviously are, the best I can suggest is you talk to her calmly about it. Offer yourself as someone to confide in. Help to educate her directly if she's interested, or just drop some information in covertly if she's defensive about it. Try to get her to visualise her future and any effect drug taking might have on what she might want to do eventually. A lot of teenagers and some even older struggle to see past the next 10 minutes, if you have the kind of relationship where she has respect for your opinion then you can aid her in seeing how this could potentially change the course of her life.
I would suggest threats and trying to forcably stop her is completely the wrong direction. You need to maintain a position that has influence. Try to avoid any action that could trigger rebellious ignorance.