"Bogambo" is most likely an attempt to compare George to an escaped Liberian negro character in the 1935 film Sanders of the River which is available on YouTube in its entirety. I have included a link here. See visual proof this is your answer at 6:37 and then watch the rest of the film to figure out why the good folks at Seinfeld felt the comparison was a proper one. Peace.
British District Officer in Nigeria in the 1930's rules his area strictly but justly, and struggles with gun-runners and slavers with the aid of a loyal native chief (Bogambo).