The mashing of the words "Snort" and "Cubicle".
It is what happens when you are at work (typically within a office-like setting, though not necessarily within a cubicle) and while browsing the internet you come across something that makes you laugh. However, due to the silent conditions you try to hold it back and it comes out as a snort. Your co-workers begin to look at you funny as you try to recover from the odd sound but also trying to enjoy the hilarity of the joke/picture/facebook post.
Also used as a subject line warning so you can brace yourself if sent by a friend.
"That picture of the lolz cats you sent me made me snorbicle, I'm lucky I still have a job"