Years ago, TNT played a trick on Neopets users by turning all the user's Neopets into mutants for 24 hours, then changing them back to their normal color.
Since that event, August 25th has been called Mutant Day. They usually just release new Mutant items on that day now. TNT hasn't pulled that prank ever since that day.
Not at the moment... You can only get mutant from the lab ray.
that homeless guy over there does --> o<<
To get a Mutant neopet, you need to give it the appropriate Transmogrification potion.
Mutant Paint Brushes don't exist. There are Transmogrification Potions (obtainable via Random Events) that do exist that can turn your Neopet into the respective Mutant Neopet that the Transmogrification can turn it into.
The weight of the watermelon on Neopets is varied day to day. Try searching 'Neopets Watermelon' or 'Neopet finders, cheats, and guides' on a searched engine.
october31
May 4th - Hissi Day
Uni Day is on March 2nd.
The ninth of September, I believe.
May 4th .
July the 17th
April 19th