Orphan Socks is from the Antibirth mod. In Antibirth, it would allow Isaac to only take damage from Curse Room doors via exiting them, similar to flight, and give Magdalene immunity altogether in Cursed! (challenge #10).
Prior to Antibirth, the item originated from the Binding of Isaac: Community Remix mod for the original Binding of Isaac flash game, where it was called "The Socks".
The "your feet feel stronger" part of the description is exactly the same as the description of Callus, which gives Isaac immunity to spikes and creep.
Orphan Socks is the rarest item that can be acquired from a Locked Chest, along with Lead Pencil.
Soul Hearts.
Curse Room doors, 
Spiked Chests, or spiked rocks, but does protect against spiked rock bridges.
Sacrifice Room.
A Pound of Flesh: Does not offer immunity against spikes placed around pickups.
Magdalene immunity altogether in Cursed! (challenge #10).
Callus, which gives Isaac immunity to spikes and creep.
Locked Chest, along with 
Lead Pencil.
The Binding of Isaac: Rebirth
