Name as many JB's as you can.

Jonas Brothers
James Brown
James Bond
Journal of Bacteriology
James Blunt
Jack Black
Jim Beam
Jornal do Brasil
Journal of Biochemistry
Jailbreak
Jelly Beans
Jack Bauer
Johor Bahru
jetBlue Airways
Jingle Bells
Jyske Bank
Jungle Brothers
Jollibee
Jenson Button
Junction Box
Jello Biafra
Jimmy Buffet
Jelly Belly
Jim Brown
Jeb Bush
Johannes Brahms
Jerusalem Bible
Juice Box
Jerome Bettis
Jacob Black
Johnny Bravo
Japanese Beetle
Juridische Bibliotheek
Joe Boxer
Jail Bait
Jerky Boys
Jura Bernois
John Burroughs
Joseph-Beth
Jonathan Bender
Jonny Bravo
Justerini & Brooks
Jail Birds
Job Books
Johann Bach
Junctional Bradycardia
JavaBoard
Joyful Being
Justin Bieber

In The Missing: Book 1 ▬ Found by Margaret Peterson Haddix, the girl calls this guy JB for Janitor Boy. That's all I can think of...

Oh, and Jelly Belly jellybeans!