Usenet Death Penalty
Usenet's heaviest collective punishment: everything from a provider that wouldn't stop its spam simply stopped propagating.
Usenet had no central authority, but news server admins could agree on things. When a provider let spam pour out of its customer base year after year and did nothing, a UDP could be declared. In the passive form, servers just refused to accept or relay articles from the provider's machines. In the active form, cancelbots issued a cancel for every single post from there, regardless of content.
The point was to hit innocent customers, who would then call the provider's support line until something changed. It usually worked fast: in the second half of the 1990s even large providers such as Netcom and UUNET found themselves threatened and cleaned up. That it was essentially extortion was no secret — that was precisely why it had teeth.