I just happened across this:
http://www.donotlink.comlink without improving "their" search engine position
...
Who uses donotlink?
Skeptics, bloggers, journalists and friends on social media use donotlink to link to scams, pseudoscience, misinformation, alternative medicine, conspiracy theories, racist / sexist blog posts, etc. without improving the search engine position of the site they are discussing.
Here's a link to DoCo:
http://www.donotlink.com/bhm8It's slightly different than a shortener. Check the link above to see.