You'll seldom catch ZZ Top without their sunglasses. In an interview with the boys, they were asked the meaning of the song.

In a 1985 interview with Spin magazine, ZZ Top bass player Dusty Hill explained: "We wrote that song when we used to tour in cars. And every gas station in the world had a cardboard display of the cheapest and ugliest sunglasses you could imagine. I have bought a thousand pair of them."
Guitarist Billy Gibbons added: "The hip trip for us was to throw them into the audience as an offering. We ran out and we couldn't get any more. So we now have to make to do with Sanford Hutton's creations out of New York. The Ray Ban Wayfarer was the original cheap sunglasses. You could buy a pair for six bucks originally. I saw a catalog from 1959, and by then they were up to eight bucks. We had to take a bad rap from an optometrist who said 'Don't wear ZZ Top's cheap sunglasses. They're bad for your eyes.' There was an optometrists' convention in Hawaii and there was a huge poster – this woman with a pointing finger saying, 'Don't wear cheap sunglasses.' I suppose I'll have to agree. There is a cutoff point where optical considerations must be taken into account. However, if you will subscribe to the lyrics: 'When you wake up in the morning / And the light is hurtin' your head/ The first thing you do when you get up out of bed/Is put on cheap sunglasses.' At that point in time, they are not intended to be used for negotiating the entire afternoon."