An inarticulate expression of
one's inadequacy or of feeling
awkward, which is then projected as an
insult onto someone else.
If you hear
people say this around you, they are probably feeling
awkward and in turn calling you
awkward or "deet" as a form of Freudian projection. A proper response would be to tell them to: "learn how to not feel awkward" or more eloquently "grow the fuck up".