My friend said he wants to rape kids

Judge not lest thee be judged.

Tell him it's one thing to have weird kinks or to fantasize about something but that he shouldn't actually do that because it's evil

You need to seriously tell his parents, like no joke that dude could grow up to be a rapist. Imagine how many childhoods he could ruin just for his own pleasure

Not even good bait.

Tell somebody. He's probably a future pedophile.

Tell everyone you know and do whatever you can to prevent his access to kids.

Rat his gnarley ass out! Sometimes it's the only way.