Google has automatically enrolled all Google Plus users in “shared endorsements.” With shared endorsements, Google will use your profile picture in advertisements to your friends. Then they discourage you from disabling the feature. In protest, Google+ users are changing their profile picture to that of the Google CEO, Eric Schmidt.
While that is hilarious, I’d rather turn it off. Go to Google+ settings -> Google+ and turn off shared endorsements. Srsly Google?!