Phrase originally brought about to describe someone who constantly wanders close by people so as to either pretend to be there friend or so as to eavesdrop on the conversation.
Typically known as a bad trait to have, a person who possesses this trait is often unsociable and often speak in metaphors in an attempt to blend in.
These people often seek places of authority in society so as to feel useful and so that people are almost required to accept them. Often taking forms such as teachers or police, they will constantly seek approval from all around them and will always attempt to gain any gossip they can find from people.
The term was later adjusted to simply "Mcgloaf" Which was then used as an insult towards people who showed tendencies such as those stated above.
Then the term was shortened further as people began to simply refer to people as "Loafs" or "The Loaf"