The Secret Laboratory (Lab Ray) 101

First, you start out collecting all 9 pieces of the Secret Laboratory Map. The pieces can be purchased from the user shops, or thru the auction or trading post (purchase prices range from 20k-70k+ np's per piece, depending on the piece, or up to 550k+ np's for a complete map thru the trading post). Sometimes you may be lucky and 'find a piece to the treasure map on the floor' while exploring Neopia/Neopets. That's always nice:) 
The nine separate pieces, once collected and put together will look like this.

What does the Secret Map do? ... the definition, according to the Neopedia is, 'When you collect all 9 pieces of the Secret Lab Map, you can then enter the secret lab. Inside this you will find all kinds of wonderous things, including the mysterious ray gun' ... however, that doesn't really answer your question, does it? So, I'll continue ...

After you have collected all 9 pieces of the Secret Laboratory Map, you need to have them in your inventory, and go to the Neopets Treasure Hunt .. once there, click on 'Laboratory' to get to the lab map area. 

If you have all the pieces in your inventory, you will get a page similar to this (click for full size).. click the 'Find the Treasure' button and you will win a prize of neopoints, which vary from person to person.
And, you will be shown the way to the secret lab (click for full size). Once you enter the lab, you'll get this page (click to full size) ..
if you click to use the lab ray, you'll go to a page that will show your pets, however, it'll look similar to mine (click to full size). Each day that you go to the lab, your pets will 'say' something different to guilt trip you into not picking them for the experiment. (I've yet to figure out if there's a scientific connection from what they 'say' to what actually happens to them when you pick them to be zapped by the lab ray gun or if it's in fact completely random).

So ... what is this mysterious ray gun? Well ....... 
Once you choose which pet to 'experiment' from the page above .. click the button and hold your breath.... The next page will tell you what the lab ray gun did to your pet. It can add to or take away from your pets stats (hit points, defense, movement and strength, etc.), or it may change the color of your pet (including painting it an otherwise expensive color like desert, faerie, mutant, invisible, and others, etc.), it can also alter the gender, or change the species altogether.