Buffy has a secret.
She's not ashamed of it, exactly. I mean, it's a perfectly reasonable thing for a girl in her position to own, isn't it? But she's never quite found the courage to tell her friends she's got one. They'd make jokes, and she'd get all tongue-twisted and blushy, as she often does when confronted by a social problem she can't solve by using violence.
She's actually had it for five years now. She doesn't think her friends suspect it's there, hidden away and covered with some of her old clothes. Mostly, it's hidden from Dawn; Buffy cringes at the thought of how her sister would react to finding it. At the very best, she'd make sarcastic comments. At worst - in the depths of her nightmares - Buffy imagines Dawn reacting with delighted glee and asking if she can borrow it and use it herself.
So she always waits until Dawn's gone out and she's sure she's alone in the house before going to uncover her secret treasure. She pushes aside the shielding cloth and lifts it out of its concealment with an air of reverence. Its weight feels heavy and solid in her grip, and the smooth hard surface warms up quickly as her body heat suffuses it. She checks the batteries still have power and runs her hand over the slightly bulbous end, wondering if she's weird for getting excited at this little ritual.
Then she puts it on her shoulder and practices calibrating the sights and priming the firing lever, before carefully putting the rocket launcher back away in its hiding place until the next time she wants to play with it...