Let a sister drink, broski. She'll learn her lesson. I don't have a problem with anyone drinking, as long as they're smart. Manage your drinking well and there's no problems. Drink water, eat food, do it in good company in a safe place, if you're not at home have a plan to get home safely, and know your limit. Everyone learns that in time, some choose to start swigging earlier than others.
I would let your sister know that I know about it, and just want to make sure she's safe. It's good you're concerned, that you care, but don't be a bitch about it.
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