BJ is the father of Dave, and the husband of Grandma. He is a powerful being that has power so strong it has to be contained constantly, lest we risk the world falling prey to his abilities of corruption. BJ is kin to the God of Destruction itself, and he is not very capable of restraining himself, so his glasses are a modified repressor made by Monarch Labs so that he can safely live amongst the mortal kind.
BJ wears a freshly-ironed light grayish-green suit at all times, whether he is out and about or just lounging around. On Sundays, he likes to wear black boxers with 8-bit hearts stitched into them instead of his regular pants. His family addresses the attire as a 'swamp suit'. On Easter every year, he is harassed because his family calls him Shrek. It's quite tragic, really.