The message of this mission is:
It is said that pygmies are full of baloney.
Have them slash each others up.
Purchase the device "Weapon Rack" on one of your isles. The quest is easier to complete, if you spawn 2 pygmies only. Click and drop one of these pygmies in front of the "Weapon Rack". Wait until this pygmy takes one weapon. Exact 20 pygmies should die like this: Click and hold this pigmy above the weapon of the other pigmy. Then the pygmy with the weapon will behead the other pygmy like a piñata.
Let 10 pygmies duel each other. To do this, let two pygmies grab a weapon and wait until they want to fight against each other. After some time, automatically one pygmy will win and the other one will loose.
This mission's message contains a minor grammatical error: "Have them slash each others[sic] up."