They are hidden somewhere in the merchandise section.
Take them to the Neggery.
You can buy them, or you can get lucky and get them for free from a random event.
You can trade them in the neggery or, let your neopet(s) eat them.
Neggs are the Neopian equivalent to eggs, but they grow on trees. They are given out in random events on Easter, but you can get them other times too. Your pet can eat neggs, or you can give your neggs to the Negg Faerie at The Neggery in the Terror Mountain Ice Caves. Neggs at The Neggery can be saved up using a system of Negg Points, and using Negg Points you can buy even rarer Neggs, some that, when fed to your pet, change it.
Some neggs are magical and gives powers. Some neggs are just regular neggs, edible for your Neopets. Some of these can be traded in for a certain amount of points at the Neggery, which can be redeemed for magical Neggs.
Via Trading post or "Hidden Tower"
In Fyora's Hidden Tower. But you better bring lotsa NP!!!
trading post or auctions or at the hidden tower
The hidden world on Neopets is Jelly World. To find it, go to Faerieland and replace the word "faerieland" in the address bar with the word "jelly." When you press enter, you will be taken to Jelly World, which is not a visible land on the Neopian map.
Smelly neggs
Well, there are two secret modes if you type, on the starting screen without spaces ferocious neggs are on the loose its will go into ferocious mode. The second mode type in ,without spaces, super extra hyper gravity mode.
You can't. Only Borovan (Adam) Neopets founder has 5.