By giving the Golden Chinchompa a food, you will be rewarded with more RS gold which is a great thing

Source: runescape
Feed your pet and they will give you RS gold
Runescape announces a new pet on September 6th which is called “Golden Chinchompa” which will help you make RS gold and also reward you valuable items once you fed him. You can’t win another one until you deleted it or after you finish raising him. Once the promotional period ends, the Golden Chinchompa will be removed and they cannot be kept as pets.
There are three special Chinchompa foods and each individual chinchompa has a favorite type:
- Dried Chilies
- Curried lard nuggets
- Pure caffeine
The Golden Chinchompa has three stages. Every 30 mins, your pet will be asked to be fed. Every time you fed him, he will reward you with RS gold. When the golden chinchompa grows to the next stage, you will be rewarded with RS gold and one item.
On the final stage, when the chinchompa explodes, you will be receiving more RS gold and 2 to 3 items along with the chinchompa gravestone. You can put the gravestone to your player-owned house.