For the same reason non cartoon characters smoke weed, to get high.
No he died in family guy in 2000
Brian the Bachelor
Brian Griffin
No.
Brian the Bachelor
A Woody
Brian Does Hollywood
That shouldn't have anything to do with their reproductive system.
Brian: Portrait of a Dog
Brian has a liberal political philosophy
Brian the Bachelor (Season 4)
Brian & Stewie's Emmy appearance & performance wasn't part of any Family Guy episode.