Amy, the shy loner

Well, you're not sure you want to do this to someone in public yet, so that limits your choices. You can think of a quite attractive girl who won't be in a crowded area.

Amy is a shy, shy girl. She keeps her dark bangs long to cover her eyes, wears jumpers with the sleeves too long if it's cool enough to get away with it, and has her skirt come below her knee unlike most of the other girls in school. She prefers to hide alone with a book rather than hang out with anyone else, and everyone tends to leave her alone. Her 'spot' is left to her alone, and when some of the younger kids stray too near, someone in your year usually steps in to keep her privacy. You've tried to get her to hang out with your group, because she doesn't seem to mind you. Sometimes you've decided that everything is too much and you just need some quiet alone time, and Amy has offered to share her spot with you in those times. But she won't leave it, and gets upset when there's too many people around. It's too bad, she's actually pretty cute.

And now you were going to put her through an orgasm. Should you tell her what's coming or stay hidden and do it stealthily?