B-3

B-3 can refer to the following:
 * World B-3 from Super Mario Bros.: The Lost Levels.
 * Room B-3 from Mario vs. Donkey Kong: Minis March Again!.
 * Graveyard Shift, mission B-3 from Luigi's Mansion: Dark Moon.
 * Level B-3 from Mario vs. Donkey Kong: Tipping Stars.

B-3