Would you buy your under age siblings alcohol?

Answer to the title: No. For so many reasons, no.

I would never buy it for them, but I did pick up my hammered sister from a party she snuck out to and I told mom I kidnapped her for sister night and let her stay at my place. Mom still has no idea

No, but I would pick them up if they ever got plastered or high and needed a safe ride home. I don't have siblings, but I would never screw them over like that.

I don't even let my brother have a whole coke...
Sugar makes him go crazcraz okay!!!

I'm the youngest, I can't really say what I'd do.

Nope, my siblings act like idiots when they have any alcohol.

Have done and and would do it again

No, I'd talk to them about why they want it and then the reasons why I'm against it. She can make up her own mind but I'm not letting her kill her brain this early in life by choice.

For my sisters? No, not a chance. For my nephews (all my brothers are older)? Yeah. One in particular, he needs some cred... I hate to say it, but he's a real dork.
Oh... also, one cousin I would have done it for, but she's over 21 now so it doesn't matter.