Here's the wikipedia entry if you want to know more about the song: http://en.wikipedia.org/wiki/Yakety_Yak 'Yak' means talking, but 'yakety yak'It doesn't really mean anything - it's just a 'catchy' little phrase that sounds good in the song.

As a native English speaker, I understand "yakety yak" to symbolize a lot of talking. It's similar to "blah blah blah", but "blah blah blah" more strongly implies that the talking was a waste of time.

The word "yak" meaning (idle) chatter first appeared in the late 1940s, possibly as a sound imitation of the Tibetan yak, a kind of ox. "Yakety-yak" entered the English language in 1958 as a result if the song by The Coasters, an American group. The etymology of yakety is "reduplication of the yak sound".

'yakety yak' represents the sound that someone makes when they talk back thus the lyrics 'yakety yak! don't talk back'