I formerly worked for a small RealEstate aggregation/publication software company with large market adoption, and a well-known competitor started deep linking t

I formerly worked for a small RealEstate aggregation/publication software company with large market adoption, and a well-known competitor started deep linking to the images within our custom-written resizing image cache server, and continued to do so after several polite requests to stop. Image traffic is the bulk of network traffic for RealEstate data, and their stollen traffic was very significant, cutting into our own available bandwidth and costs. We slyly added referrer-based logic which would, with 1/20 probability, serve the Goatse.cx image instead. Needless to say, within 48hrs we never received another deep link request from that competitor.