Lyric discussion by scottme 

This is sheer poetry, as indeed are a great deal of Costello's lyrics. The words in this song are overloaded, double meanings exploited and hidden meanings deftly stitched into what has in this case become pretty much an acknowledged jazz classic. There have been so many covers of this song, but I've yet to hear one that improves on the original. IMO Tracey Thorn of Everything but the Girl comes closest, but ultimately fails through a less than stellar arrangement.

So what's it all about? As I see it, he is singing to his ex-lover, about a narrow escape he's just had with a different girl, who in many ways was almost like his ex. He flirted with this girl, but caught himself in time, realising that he was well on the way to making a fool of himself, by trying to repeat his affair with the ex - an affair that we must assume ended in tears, or at least ended with him (and her) being blue.

An error occured.