Literally, a low life that is able bodied, yet lives off government assistance. I.E. Welfare, WIC,
Food Stamps etc. etc.
In the film Forrest Gump, Forrest asks Lt. Dan what he's doing now when he sees him for
the first time after they arrive home. Lt. Dan, who has lost both legs and is confined to a wheelchair, states, "Living off the government tit."
The phrase is a reference to Lt. Dan's receiving a monthly stipen
for the loss of his lower limbs.
In recent years, the term has a negative connotation and is often used to describe healthy welfare recipients that are able to work but choose not to because they are satisfied with their welfare checks for doing nothing.