Name of the larval phase of development in insects of the order Diptera (flies) that have laid eggs in a persons rectum. Flies are often drawn to the scent of rotting or decomposing flesh or feces where they then lay eggs. Hence when a person neglects to clean their rectum of fecal debris larval gestation may occur.
Can also be used to describe a person of disgusting personal hygiene.
Justin the hobo had a horrible case of ass maggots because he never cleaned his butt crack after he craps behind the dumpster.