Maybe I'm just a little chaotic/neutral, but I like @ZydoSEO's idea. I'm not opposed to Pinterest scraping my sites (see my Pinterest copyright infringement thread) but I do respect the right of a site owner to reduce, prevent and even fight back against unwanted use of their site. So here are a list of ideas:
- cause Pinterest crawler to hang somehow, using their system resources
- cause Pin crawler to grab the wrong image, preferably one with undesired content like skin diseases, etc
- cause a never ending redirect loop of some sort
- redirect to a large site that is known to go after copyright violators
- automail a DMCA takedown notice
The last one is my favorite, but creating something of a random mix of the above would probably be fun.