A guy who is incredibly dumb/an idgit. Most often used when a guy does or says something especially stupid.
Guy: Wow, did you dye your hair blue?
Girl with blue hairpiece: No, silly, it's not my real hair. You're such a digit.
Girl with blue hairpiece: No, silly, it's not my real hair. You're such a digit.
by L-J Pookie April 03, 2005