A large, slightly overweight heterosexual male that has little to say and lacks a sense of masculinity. He of course tries to exude a pretense of manhood by eating a lot of meat, but may go up to his room for 'alone time' and start crying for no apparent reason. It would not be uncommon to hear of a female winning a physical battle with a meat oaf.
Hey Fred, look at that Meat Oaf being beat up by four school girls! I betchya he could use a big steak afterwards!