The act of turning away from social networks and/or communication in order to get some alone time and/or relief from the excessive use of online social networks/communication. This does not mean the sheller does not use dark social mediums such as e-mail and/or text messaging.
Adam: Hey Steve, why are you not on facebook anymore?
Steve: I told you!! I'm shelling for a few months. I can't be too addicted to shit like facebook
Adam: You can't be in your shell forever, you'll be back.