Those who are completely unaware of either their current situation, or their surroundings, or their own inadequacies. They exhibit remarkable obliviousness to their overall presentation to the world, or the fact that they are hindering others through their incredible obliviousness
Incredible! That driver is blissfully unaware he's holding-up an entire line-up of cars behind him. What an oblivio!
Refers directly to the expression "10 pounds of shit in a 5 poundbag" -- in other words, having too large a quantity of something inside too small of a container.
My mother had quite an oblivit going with the all the meatballs she had cooking in that little skillet.