The Marathon is a now discontinued candy bar. The "bar" was three lines of caramel which were braided (to a length of one foot) then coated in chocolate. The Marathon was roughly the size of a twelve inch ruler, however since it was in a loose braid, there was a lot of empty space.

When I would buy one of these, I would take the whole thing out of the package, roll it up — little pieces of chocolate cracking off onto my hands — into a little tire shaped mass and then put the entire thing into my mouth. Today, just thinking of that makes my teeth scream. Sure the chocolate's good, because hey, it's chocolate! But have you ever made caramel yourself? It's sugar, water, and heat — although I'm sure the Marathon variety had a few other chemically ingredients just for fun.

One hot summer day I bought one at Happy Market and as I was walking home un-wrapping it, I noticed that the chocolate had this weird whitish look to it (I think this discoloration is caused by chocolate melting and then cooling to a solid again — a process that, from this day forward, I shall refer to as "chocolate weirdification"). I thought to myself

"Self, something might be wrong with this chocolate".
Yet the sweet siren song would be too perfectly voiced. The variegated chocolate calling me — "oompah loompa" it told me in whispered tones that passed by my ears like a soft wind through the leaves of the sheltering trees. Yep, food poisoning (or worse) be damned, I ate it anyway.

The only current candy bar I've heard that is similar (though a bit shorter) is called the "Curly Wurly" which apparently is sold in Australia and some parts of Europe.

Notes: mkb let me know "that chocolate discoloration is called blooming".
Zerotime told me "The Curly Wurley is a bit shorter; about 20cm or so".
Batu Khan enlightened me that "The Curly Wurly is also a product in Australia".
And belgand related the following enviable story tidbit: "The whiteness on chocolate is technically known as 'blooming'. This indeed occurs due to melting and resolidifying and is a frequent occurance during the summer months. I learned all this while spending the summer working at a Godiva shop one summer. Quite frankly the only major change is cosmetic, but it was enough to cause all the bloomed chocolate to be written off and become free to employees. Since it was summer I basically spent the time eating a great deal of chocolate. I can attest that there is absolutely nothing at all wrong with eating chocolate that has bloomed ... egad, just noticed that mkb had already set you straight"
Thanks all!