[Kaneki considers his answer. How to frame it. He could just say something shocking - though he doesn't know that Dipper would be shocked - or he could explain properly.]

At home, there's a faction of ghouls who want-

Well, I'm not totally sure what they want. It's something I'm trying to figure out.

[One of many things.]

Regardless, they have no problem walking over other, weaker ghouls, like I used to be. I happened to get caught up in things with them, and I happened to get the attention of a particularly sadistic member of their group.

[He pauses. He doesn't know how old Dipper is exactly, but he feels like he's showing a kid an X-rated magazine.]

He tortured me for ten days. [He doesn't have to go into detail, he tells himself. He doesn't have to talk about having his fingers and toes cut off over and over, things like that. About how counting backwards from 1000 by sevens will actually keep you from passing out during all of that.] Heh heh...your hair really can turn white overnight if you've gotten enough of a shock. I always thought that was a myth.

[His expression is oddly soft, considering the topic, almost like he's being self-deprecating on behalf of his past self.]