Someone's put a black streak on Mars.

[TimberWolf]

As a nipper I thought that Milky Way must be the only food product that was marketed as having no food value - "The sweet you can eat between meals without ruining your appetite". Those ads put me off buying Milky Way in my hiking days; Mars and Topic bars were what I took with me instead.

As we all suspected, Mars Bars have been getting smaller:

In the second half of 2008, Mars UK reduced the size of regular bars from 62.5g to the current 58g. Although the reduction in size was not publicised at the time, Mars claimed the change was designed to help tackle the obesity crisis in the UK. The company later confirmed that the real reason for the change was triggered by rising costs.
Mars bar - Wikipedia, the free encyclopedia

Use as a reserve currency:

It has been observed on several occasions that the price of a Mars bar correlates fairly accurately with the change in value of the pound sterling since World War II.[18]

Deep-fried Mars bar

Main article: Deep-fried Mars Bar

This is a Mars bar which has been coated with batter and deep-fried in oil or beef fat. First reports of battered Mars bars being sold in Stonehaven[citation needed], Scotland date back to 1995.[13]

Deep-fried Mars bars are available from some fish-and-chip shops in Britain, Ireland, Australia, New Zealand, Canada and the United States.[14][citation needed]

[Sysman]

Use as a reserve currency:

It has been observed on several occasions that the price of a Mars bar correlates fairly accurately with the change in value of the pound sterling since World War II.[18]

Alan Coren had something to say about that in a brilliant 1970s short story / essay* on inflation and Post Office Savings Accounts (which paid peanuts in interest). His position was that it wasn't worth saving in inflationary times.

* I can't remember the name of the book, but it was a collection of short stories. Very funny, though it would be dated nowadays.