As each demon's inside is unique, Twayne is shown to have a sun and some living organisms inside his body in the episode "Journey to the Center of Twayne". One hour outside Twayne's body equals to one day inside.
After Jerry "The Fire Ant" McMillan has escaped into Twayne Boneraper's body, Leonard Powers shrinks Mark Lilly, Francis Grimes and himself to microscopic scale and enter Twayne's body as well on a motor vehicle to track down Jerry.
They are caught by the stomach bacteria and brought to a village. The village has been strategically built to avoid the food slides. There they meet the chief and his daughter Princess Chlamydia.
Grimes soon marries the princess. Jerry is enraged to discover the three men followed him and burns down the bacterial village which kills the chief.
The three pursue Jerry all through Twayne's body. Mark finally discovers Jerry at Twayne's eye. He succeeds in persuading Jerry to giving up his anger but Grimes arrives and kills Jerry with a bone spear. They bury Jerry in Twayne's sinus cavity.
When they start to grow back to their original size, they race out of Twayne through his ass.
Grimes keeps in touch with Princess Chlamydia through Mark's cellphone, which has been behind in Twayne's body.