The proud owner of a herd of "Mountain Pigs," pigs which can do everything except fly, he is constantly worrying about them, and once, when they got loose, stated that he was "Going out of his mind" with worry. This may be true, as in a cutscene, he went cross-eyed while "cuckoo" sounds played. He also slapped himself several times.
According to Vinnie Pappalardo, a unnamed employee used to work for him and failed him, which caused this person to "buy the farm", even after Vinnie told him it was a terrible investment. Since Jethro owns the farm is is possible that he used to work for Vinnie.