I wonder how, I wonder why
Yesterday you told me 'bout the blue blue sky
And all that I can see is just a yellow lavatory

The story:

It wasn't really bad. I had been listening to the song carefully on the radio before, being a bit puzzled. At some point I just accepted the guy just was singing about a yellow toilet although it didn't make sense to me. But hey, that never had been a criterion in pop music now had it? Later I was in the car with a friend and the song was on. I sang along with it and he was really amused. He told me what he made of it and since then I heard lemon tree too. It seems less funny yet doesn't make more sense, it might just as well have been lavatory.