You compare the price of egg to comething completely unrelated.

Ahhh, I see now. This is a colloquialism. Basically, it means that the statement that was made has nothing to do with the topic at hand.

For example:

Person 1: IQ measures intelligence

Person 2: Someone who graduates from Harvard is more intelligent than some one doesn't

The correct response would be "So what does that have to do with the price of eggs?" because graduation from a specific educational institution is totally unrealated to whether or not IQ measures intelligence.

http://en.wikipedia.org/wiki/What's_that_got_to_do_with_the...%3F