Slipped Rib is an unlockable passive item added in Booster Pack #5.
- Spawns a bone familiar that circles around Isaac and reflects enemy shots.
- The reflected projectiles deal 5 damage if they would've hurt Isaac for half a heart, and 10 for a full heart. Enemy damage modification from item effects or by stage has no effect on this.
- The familiar does not deal contact damage.
- BFFS!Increases the size and damage of familiars.: Familiar is bigger and protects more of Isaac.
- This item is a reference to slipping rib syndrome.
- This item may be a reference to the Adam and Eve story in Genesis, where God takes a rib from Adam's body in order to create Eve.
- This item may be a reference to the NES game Castlevania 2: Simon's Quest, where Dracula's rib is an item used as a shield that protects from projectiles.
- This item is Edmund's favorite Booster Pack item according to _Kilburn.