1. It has become a common term is the USA for calling someone a Numpty
(minus the endearing portion of the insult). It's come to mean all of the above lazy, idiot, carefree fool, with a dash of schmuck.
2. It has also started to be used more and more to mean someone who is happy to be ignorant. It's sort of a blend of sheeple and schmucks.
1. That guy was such a total shmeg he took up two parking spaces with his little scooter.
2. Those shmegs in the US actually went out and voted for Bush for a second term.