You call google shit on someone who feigns knowledge of something without admitting they just looked it up on some search engine.
Chatting with someone online you wonder who did that Bertha Butt song and five seconds later they say "I think it was Jimmy Castro or Castor or something like that" and you know they're blowing it out their ass, so you say "Google-shit!"
When you are in the middle of looking something up and you suddenly have to run to the potty and you can't wait to find out what google has to say about something, so you bring your laptop into the can.
This article says something about Jimmy Swaggart. I know I know who that is but I've got to double-check on google. Oh my god, too much coffee. Dude, I gotta go take a googleshit. Hope your laptop doesn't smell when I come back.