The Drifter is a character from the episode, "No Weenies Allowed." He drifts along towns, finding tough clubs, based by his name. He somehow knows that Reg's club is pretty tough.
The Drifter looks exactly like SpongeBob only he has thick, glossy, black hair. Another similarity to SpongeBob is that he is also voiced by Tom Kenny. The Drifter claims to be tough, though Reg never told him to prove it before letting him enter the Salty Spitoon. He pulled his hair. But it never hurt the drifter, implying that he is quite tough.
When the Drifter asked to go into the Salty Spitoon, Reg thought it was SpongeBob wearing a wig, and tried to pull the Drifter's hair off, but when the real SpongeBob appears wearing a rainbow wig, Reg apologetically fixes the Drifter's hair, and lets him in.