Randall is a goat who was first revealed as Delivery Doug's business partner in the episode O is for Opposite. Randall was laying eggs for Doug's egg salad sandwiches, but was let go when Olympia suggested that Doug use chicken eggs.
In Who Let The Doug Out, Randall is running a "secret egg racing club" (in Doug's words) which Doug is banned from due to cheating. Randall is now able to talk thanks to a Goat to Human voice machine built by Doug.
"Ha Ha Ha Ha Ha. Foolish Douglas."
"You know you aren't allowed here anymore, Delivery Douglas."
"Foolish Humans. You shall be covered in egg by sun down. Let the race commence!"