GB Bug is an unlockable passive item added in Afterbirth.
- Spawns a familiar that bounces around the room, deals 8 damage per tick or 120 damage per second and applies a random status effect to enemies it comes in contact with.
- The familiar also has a chance to re-roll pickups that it passes over into other pickups, chests, or items, in an uncleared room only (with at least one enemy alive).
- GB Bug can block projectiles.
- GB Bug does more damage per second than The PeeperSpawns a familiar that floats slowly around the room on a zig-zag pattern similar to Boom Flies damaging enemies it passes through., with the added random status chance.
- This item's in-game appearance may be a reference to "Missingno.", a famous bug occurring in the first Pokemon games.
- As Edmund confirmed on twitter the pickup quote "Game breaking bug, right away!" is a reference to a quote by Phil Fish in Indie Game: The Movie, where he says the exact same words when a bug is discovered in FEZ on the first day it is being shown at PAX.
PC 9B7E 3G67 (Treasure room adjacent to spawn, curse of the labyrinth) (hard mode only)
PC GZWT H4LE (First floor treasure room) (Normal mode only)