What is The Big Grin?
1.
A clueless, Manic-depressive moron who is always "in your face". This is one of those guys that you carefully try to avoid at social gatherings because they have no social grace. They will babble on about how great their life is one minute and how much it sucks to be them the next.
They want to take on the world, but then they don't have time for it. They get mad at you when you remind them of their commitments, as they've moved on to bigger things in their head.
The Big Grin cornered me last night and told me all about the big promotion he got at work, when I agreed that his life was good he told me about the long hours and how it sucks to be him.
When I remined him of the paperwork he had due, he got angry at me because he had since gotten bigger and better things to do.
See