The Drifter is a minor character and has a one-time appearance in the episode "No Weenies Allowed." He looks exactly like SpongeBob, but with black hair instead, as SpongeBob doesn't have any hair at all. He may seem like SpongeBob with a wig, but he is some other character who looks exactly like SpongeBob, as revealed when Reg tried to rip off his hair. Later, the real SpongeBob comes with a rainbow wig on.
He only appeared in a short cameo trying to get into the Salty Spitoon, though Reg thought he was SpongeBob, and tried to rip off his hair, but the hair stays on and he realizes its real and is immediatly scared and embarressed, and lets him into the Salty Spitoon.