"something considered to be outstanding. 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."
When someone pretends to be sweet and child like but underneath they are still wild and unpredictablelike a Bear. Typically evil in nature pretending to be good.
Adam: I like Eric, he's such a nice guy.
Clint: No Way, that dude is just a Bear wearing Footy Pajamas, you can't trust his outer apperance.