You know, you should always trust your older brother. She's being so kind to you, she picks you up from school, buys you ice cream, she even lets you have a few drags of her cigarettes. If you're really good, she'll let you have some of her weed too. Yes, she does have to shotgun it to you, trust her, it would be far too strong for you if you smoked the joint directly.
And it doesn't matter that you don't quite remember what happened after the first few hits, or that it felt weird when she started sticking her tongue into your mouth. It felt good, didn't it, even if you did need to hide those bruises and bite marks on your shoulders and neck from your parents. Your brother just wants to make sure you feel good, and she promised to let you have your first beer next time she picks you up from school, so long as you don't tell your parents why it takes so long for her to drive you home every night.