As with most underground sexual activities, there is no dictionary definition for extreme fetishes. But perhaps a general definition would be a fetish that would provoke not only consternation but also revulsion in an otherwise open-minded person.
Some examples:
- Insertion of large objects in body cavities, usually the vagina, anus, or mouth
- BDSM activities involving extreme pain or blood play
- Scat, enemas
- (more entries needed, however, bear in mind, VW policy does not accept entries that link to web sites that are considered bizarre, obscene or illegal)