Who is Jack Patton from Hocus Pocus and what is their importance?

Jack Patton is Eugene's brother-in-law. Jack is very tough and talks it. He believes everything is a cosmic joke and the laugh is mostly at humanity's expense. Jack's catchphrase response to every bad situation is that he would "laugh like hell" at it if he had the muster. But he mostly remains silent and does what he is told to do by others. He dies in combat during Vietnam.