Memories of Dreams Long Gone

I have never fully understood how dreams can contain things that have never and probably never will exist.

Example:

I had a dream once that I was in my room, and my friends came over to play some music for me.  One of them was a friend I have in real life who is quite talented with the guitar, but the other three were a singer, a bassist, and a drummer that I've never met, but the implication was that they were a band.  Somehow, they'd managed to squeeze a full band set of instruments into my room in about thirty seconds and start playing.

The song lyrics went:

"Oh, it's a maritime monday,
oh, sweet release,
oh, it's a maritime monday,
oh, I'll never be free."

Or something like that.  It was then that I looked at the wall, and there was a giant picture there of psychedelic, swirling colors that shifting around continuously.  That woke me up, because it was way too out there even for my twisted mind.  It was strange, because I normally have this picture on my wall:

 

The one on the left is the picture, and the one on the right is my cat.  Strangely similar.