Watermelon activists are out in force during Earth Day and Earth Hour.  A Watermelon is  green on the outside and red on the inside, and is a term of derogation for environmental activists with socialist principles.  After the fall of the Soviet Union thousands upon thousands of dedicated Socialists were cut adrift from their allegiance to the USSR and Comintern.  Their Church of Communism had collapsed, and they were cast out into the night wailing and gnashing their teeth.  Many quietly lost the Faith and committed the ultimate apostasy by Selling Out and rebuilding their lives without their subscription to The Socialist Worker.  Many more, however, never lost their convictions and simply transplanted themselves into the burgeoning environmental movement where they agitate for the destruction of Capitalism and Western Civilization in the name of a new deity, Gaia, in place of Marx, Dialectical Materialism and the Worker’s Paradise. This is why the Sierra Club, once a serious and sane environmental group, has devolved into lunacy.  Probably the most outre among these is the Voluntary Human Extinction Movement, save_the_planet_kill_yourselfwhich argues that humans should voluntarily refrain from procreating until Homo Sapiens Sapiens is extinct.  Logically, this cannot be justified as being done for the benefit of the children, so it must be a voluntary human sacrifice to Gaia.  I am not certain whether the makers of this banner are serious or being merely ironic, but I do notice that those who promote these kinds of ideas never lead by example.

And it is, as you would expect, all backwards.  Matt Ridley explains: