It basically means that doing or saying something wrong or stupid can result in a lot of unpleasant reactions, ranking from laughing about it to serious criticism and even protest actions on the internet.
The amount and pace of the critique then add up to a storm that the 'victim' can not defy and that can badly harm his or her reputation.
Now, there is a new phenomenon emerging that is exactly the opposite, honoring people or institutions for good work: the candystorm.
It can be traced back to the German politican Volker Beck (The Greens) who initiated the first candystorm in November 2012 as a measure of support for his colleague, Claudia Roth. In an inter-party election she wasn't elected to run the national campaign, and it was obvious she was deeply disappointed. It was unclear if she was running for chairperson of the party again or not.
But as her fellow party members wanted her to run for this office, they felt that Roth needed encouragement. So they invented the Candystorm and urged party members to participate in it via Twitter and Facebook. The opposite of a shitstorm? #claudia2moreyears.
This candystorm action brought a variety of compliments and proved to be very successful. Claudia Roth, impressed and touched, decided to run again. This time she won and the good mood came back.
This story potentially could have been a minor incident, but the media picked up on it and reported it everywhere. In the meantime, another Candystorm has appeared, 'hitting' the Financial Times Germany that went out of business.Their good work was praised all over Twitter.
The Candystorm term seems to be in everyones mouth right now, but it remains to be seen whether this is a short term phenomenon or will be as established as the Shitstorm is nowadays.