Lydia the Tattooed Lady

Why does the human brain grab songs and repeat them over and over and over again?

I often get songs stuck in my head. Usually it's a song that I've heard recently, (whether by choice or otherwise) but sometimes the songs appear because they relate to something that's going on. For example, when I have to go out in the rain, I often get a rain themed song, usually 'Raindrops Keep Falling on my Head' (often with the childhood addition of: If they were rocks I'd soon be dead...) Sometimes it's 'Why does it always rain on me?' by Travis, or the appropriately titled Rain by Madonna. Rarest of the rain songs is 'Singin' in the Rain' (Probably because the prospect of going out in the precipitation rarely makes me feel like dancing around with an umbrella)

When I'm walking up a big hill, I usually get Climb Every Mountain from The Sound of Music. (Thank you very much Reverend Mother...) Actually it also pops up when I'm walking up a slight slope, which is a bit ridiculous... Climb every slight slope...

For some reason this morning I had the theme from The Man From Snowy River stuck in my head while I was messing about with my horses' hooves. There was no galloping down a mountain involved, no colt (from Old Regret or otherwise) had got away, and my horses definitely weren't snuffing the battle with delight, they were just standing around...

I guess there's a horse link, so it's not that weird... but why (oh why!) did I have Lydia the Tattooed Lady stuck in my head just now? Why does it pop into my head so frequently?

I'm really not sure which lyric might set it off, but here's the YouTube video so you can share in the delight of having the Marx Brothers pop into your head when you're cleaning the house, walking the dog or otherwise nowhere near any tattoos, ladies or men with large moustaches and cigars. Enjoy!