When a ship approaches the Equator, crew members who are crossing for the first time must appear before King Neptune and his court to demonstrate their worthiness as subjects of the sea. Proof is exacted through tests and punishments that can range from the mildly embarrassing—singing a song or reciting a nonsensical rhyme—to much more grueling treatments: running the gauntlet, tarring and feathering, or crawling through slops. The custom earns the sailor or passenger little more than a certificate and the right to call himself or herself a "shellback."