When enough orks gather in a single place, some of them become powerful psykers known as weirdboyz. GorkaMorka however don't have enough orks for this but still have orks with psychic potential.
These fonts of waaaagh energy are known as Wurrrdz, and are unpredictable to say the least.
Sorted out the necessary bits for a mob of 10 boyz. One will get a rokkit launcha, and the nob a kombi-weapon. Mostly old & new Orks, some Chaos Warrior & Marine bits and some other scrap to almost fill the required number of body parts & weapons.