Cas is a beaver and is apparently a friend of Ket's. His outfit is an open orange puffy vest and a pair of denim hot pants (which appear to sport a good bulge), with extra thick round glasses over his eyes.
He lives on the other side of the Southeast Beach in a log cabin, which is full of dakimakura–or body pillows–of Isadora, who himself seems to be a slim-looking lizard with a huge cock. He's most likely an otaku, given that he is quick to fluster, has a range of posters and aforementioned body pillows, and has a cliché nerdy look to him.
He helps out Joe by lending him his “Ass Masters” book, enabling him to slam downwards with his bare-naked rump.