Alternative forms 
- cat's pyjamas (UK)
A slang phrase coined by Thomas A. Dorgan. The phrase became popular in the U.S. in the 1920s, along with the bee's knees, the cat's whiskers (possibly from the use of these in radio crystal sets). In the 1920s the word cat was used as a term to describe the unconventional flappers from the jazz era. This was combined with the word pajamas (a relatively new fashion in the 1920s) to form a phrase used to describe something that is the best at what it does, thus making it highly sought and desirable. Similar phrases that didn't endure: the eel's ankle, the elephant's instep, and the snake's hip.
A report in the New York Times of a publicity stunt by an unknown woman in 1922, in which she paraded along 5th Avenue clad in yellow silk pajamas and accompanied by four cats similarly dressed, may indicate the phrase was already current by that date, as the "cat's meow" certainly was.
- (idiomatic) A highly sought-after and fancy example of something, usually referring to inanimate objects.
- That new car was really the cat's pajamas.
See also 
- ^ http://www.randomhouse.com/wotd/index.pperl?date=20010102
- ^ Mark Israel, 'Phrase Origins: "The bee's knees"' alt.usage.english FAQ file, http://alt-usage-english.org/excerpts/fxthebee.html
- ^ New York Times, November 6, 1922:'PAJAMA GIRL AND CATS OUT': “Sunday afternoon strollers in lower Fifth Avenue were treated to the unusual sight yesterday of a young woman clad in transparent yellow silk pajamas, escorted by four cats, also clad in pajamas, leisurely making her way along the avenue...” The phrase is unlikely to originate with this incident however as the words “Cat’s pajamas” are used by one of the policemen at the scene when voicing his suspicion that the woman intends to get herself arrested: “Cat’s pajamas,” mused one of the patrolmen, “Wait a minute, I think there’s a publicity scheme afoot.”
- ^ New York Times, August 6, 1922:"The flapper tells her "cakie" that a Chauve Souris sundae is "just the cat's meow"."