The Stealthy Uni can be obtained via the Rainbow Pool, by using a Stealth Paint Brush (only 6,000,000 neopoints) on your Uni. Further, methods like Labbing your neopet, or using a FFQ, are also possible.

The brightness is part of what I like so much, though you have a point about that being not the best clothes for stealth. Paint yourselves a Stealthy Uni today!
Lenny Shetty
Lenny treats Neopets like a long-running side quest that somehow turned into a lifestyle. Part archivist, part bug-spotter, part professional “wait, why does this work?”, they dig through updates, dailies, and site oddities so other players don’t have to. Equal parts curiosity and stubbornness, Lenny is here to poke buttons, break things (accidentally), and report back with receipts.