Sock Goblin
Sock Goblin · neutral mob · Femboy Mod
A small green goblin with 10 health that never attacks. Within 16 blocks it looks for a player who carries legwear: Programming Socks or Fishnet Tights in the inventory. It sneaks up, takes one pair and runs. Socks you are wearing are safe.
The theft shows above the hotbar as A Sock Goblin snatched your Programming Socks!.
Getting the socks back
Kill it. It drops the stolen pair and one Lost Sock. While it holds socks it never despawns, so it can be hunted down later.
Since 0.3.0 goblins slide on polished floors like a player in socks, so indoors they are easier to catch.

Laundry baskets
A Laundry Basket with socks in it is raided before any player. Nearby players see A Sock Goblin raided the laundry basket!.
Where it spawns
At night and in the dark, alone: forests, taigas, plains, sunflower plains, meadows, cherry groves, snowy plains, savannas and swamps.
Turning theft off
With the game rule femboymod:sock_goblin_theft set to false, goblins still spawn and still drop Lost Socks, but they only giggle.
Two Lost Socks make a pair of Programming Socks, so goblins are the crafting route to the socks.