The Atellan Farce (Latin: Atellanae fabulae or fabulae Atellanae, “Atellan fables”; Atellanicum exhodium, “Atellan roast”), also known as the Oscan Games (Latin: ludi Osci, “Oscan plays”), were a collection of vulgar farces, containing lots of low or buffoonish comedy and rude jokes. It was very popular in Ancient Rome, and usually put on after longer plays like the pantomime. Named after Atella, an Oscan town in Campania, where they were invented, they were originally written in Oscan and imported into Rome in 391 BC. In later Roman versions, only the ridiculous characters read their lines in Oscan, while the others used Latin.
About.com Discussion on Atellan farce and Roman fabula in ancient theatre.
Tupelo Community Theatre Discussion on fabula in Roman theatre.
Tupelo Community Theatre Definition of the term fabula.