He has been in jail five times for assault on his little brother and he has been known to bully both his brother and even his father. Jefferyjaw was why Jabberjaw had to quit High school. The excessive bullying got so bad on Jabberjaw that Jefferyjaw once threw him off the building and into the marching band below, killing two members of the band and hospitalizing Jabberjaw for three months.
Jefferyjaw was also very greedy as he wanted the family money for himself so he decided to sell Jabberjaw to a masked demon. He was about to kill Jabberjaw Senior when he disappeared suddenly and it made him think he died.
Years later Jabberjaw came with the Radioactive Uber Clan to stop his evil brother once and for all. The two fought until Jabberjaw Senior came and knocked out Jefferyjaw.
After that incident, Jefferyjaw now resides in RUC Prisons. He is sometimes brought out by Jabberjaw himself to be part of Jabberjaw Theatre where he and the audience can humiliate him by tarring and feathering him, making him eat onions which he's allergic to, making him watch a video of his previous girlfriend dying in a car crash over and over again, pelting tomatoes at him, and at one occasion castrating him live on television to expel all the sins he has done.
Jefferyjaw has three more years until release.