Cat Nuts 

a rare disease where your balls grow whiskers and crave tuna

I have cat nuts

Cat Nuts by Health 2 May 17, 2009

cat's nuts 

This phrase is a descriptive term used to accentuate the coolness or craziness factor of a person, place or thing.
Killer alternative to the "Cat's meow".

As in "This shirt is the cat's nuts."

cat's nuts by phenomena April 30, 2006