I was once an innocent pvp player on the best server ever. It was on this server that I found one of these on my second day in a snow storm running from some wolves. The little caption said “feed Mejo berries to taim”. I figured he was a cute little guy so I tamed him up and named him jerboa. After a couple of hours I managed to loose the wolves and find my way out, only to find more dire bears and run away with my ass on fire. Once I found my tribes camp I set him down in my hut and took a nap. When I woke up my friend geoslayer143572 gave me a piece of element and told me to feed it to him. I had no clue why but I trusted him. I walked up to Jerboa with the element in my hand and he went ballistic. I could tell he wanted it pretty badly so I gave it to him. From that moment he was known as Kong.
First of all, keep him out of the light, he hates bright light, especially sunlight, it'll kill him. Second, don't give him any water, not even to drink. But the most important rule, the rule you can never forget, no matter how much he cries, no matter how much he begs, never feed him after midnight.