Simply fill your inventory with full stacks of mejos. No crops. Make sure to have nothing else in inventory or hot bar. Armor is fine. Be in close quarters with it. Taming pen preferred. It will steal and stack and start taming. I've had moments that it poops 3 times and doesn't lose taming effectiveness. It might stick its head in the corner and stop stealing from you. Just move around until it turns and comes at you. Tamed a 150. Had 30 stacks of Mejo berries on me. Probably only needed half.

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