Don't install the extension.

The bitter.io extension inject advertisements on webpages replacing the original ones.

I checked with:
  - http://coinarge.com/fciUm9E (and many other url shorteners)
  - http://virtualpub.io (after login)
  - http://bitfun.co/games (sometimes)
  - http://smurfgo.com/
  - https://www.swingbtc.com/.