One of the main characters in J.R.R. Tolkien's 'The Hobbit'.
Bilbo Baggins is a hobbit who lives in the Shire in a town called Hobbiton. He leaves is lazy life to go on a quest for dragon's treasure, and he finds the One Ring of Power on the way. He eventually gives the ring to his nephew, Frodo Baggins.

A man who messes around with other men, but no one would ever know by looking or talking to him. Used by gay black men to identify masculine gay men or DL Brothas.

A hobbits sex toy.

To greedily grasp for the joint when it is shown to the Bilbo, usually accompanied by a fierce look in the eyes and raging desire. Similar to the scene from LoTR: The Fellowship of the Ring when Frodo shows Bilbo The Ring and he freaks-a-leak and goes for it.

someone who totally fucks up, like in baseball when a ball is hit to the third baseman and he totally muffs the play

An asshole with hair on the inside and covering it

For whatever reason, a bilbo became the name given to an individual who wasn't given much chance of survival during games of Advanced Dungeons & Dragons. For added humililation, the name was pronounced in a low voice with the emphasis on the O. Also used to designate an NPC who was clearly about to die in a poorly disguised plot twist.