Used to be a kid at our school who would take a shit directly into a few sheets of bogroll, then wrap it up like a small parcel and lob it at people, where it'd explode on contact.
The worst scat story I've heard is so vile I won't repeat it here, but someone once told me about a sexual practice known as 'frosting', which I'm not sure I believe, but involves, er...well, has anyone else heard of it?