The term "cat's pajamas" comes from E.B. Katz, an English tailor of the late 1700's and early 1800's, who made the finest silk pajamas for royalty and other wealth patrons. This phrase is often likened to and/or confused with the 20's term "cat's meow".
A good midwestern description of onegreat gal or guy.
Kinda like when you have an asshole who is bullying someone and instead of leaving them hanging, you answer the bully by saying “no man, you got it all wrong-they are the cat’s pajamas”