Borderlands 2Loot Midget

Loot Midgets are renamed to "Legendary Loot Midgets" in UVHM and have a 5% Spawn Chance each time you open a container.

In UVHM Loot Midgets have a chance to world drop: Legendary/Pearl Weapons 7.4%, Legendary Grenades 2.1%, Legendary Class Mods 1.5%

A guaranteed place to farm them is in Dahl Abandon.
For them to spawn you need to:

1. Get the quest "Space Cowboy" from Moxxi in The Backburner.
2. Play the quest until you need to pick up the nude magazines.
3. Fast Travel to Dahl Abandon and run to the left.
4. When you open the outhouse where the magazine is, a Loot Midget will spawn.
5. If the Loot Midget didn't drop your desired gear reload and try again.

But DON'T pick up the magazine in the outhouse!!
If you pick it up by accident Alt + F4 out of the game.