Also used to describe another person who is genial and fun to be with.
This term has been recently popularized by the movie 'The School of Rock'.
Those crazy rinestone studded platinum teeth are the cat's pajamas!
Pinkie Pie: She's the head of the pack, all right. The pick of the litter! The CAT'S PAJAMA'S! Oh, wait! Why would Applejack take some poor kitty's PJ's? That's not very sporting of her.