Disco biscuit is a popular slang term for the drug ecstasy, which is commonly used recreationally in party or club scenes. There are several synonyms for disco biscuit, including E, X, Molly, and MDMA. These terms refer to the same drug with varying degrees of connotation. While E and X may be perceived as cool or edgy, Molly has a more playful and feminine vibe, and MDMA is the clinical term used in medical contexts. Regardless of the word used, ecstasy is a powerful substance that should be used with caution and only under medical supervision.