Bistromathics
I'm really enjoying the new series of The Hitchhiker’s Guide to the Galaxy on Radio 4. One of the funniest things so far is Bistromathics - the advanced number theory that powers spaceships:

Bistromathics itself is simply a revolutionary new way of understanding the behaviour of numbers. Just as Einstein observed that time was not an absolute but depended on the observer's movement in space, and that space was not an absolute, but depended on the observer's movement in time, so it is now realized that numbers are not absolute, but depend on the observer's movement in restaurants.

The first non-absolute number is the number of people for whom the table is reserved. This will vary during the course of the first three telephone calls to the restaurant, and then bear no apparent relation to the number of people who actually turn up, or to the number of people who subsequently join them after the show/match/party/gig, or to the number of people who leave when they see who else has turned up.

The second non-absolute number is the given time of arrival, which is now known to be one of those most bizarre of mathematical concepts, a recipriversexcluson, a number whose existence can only be defined as being defined as being anything other than itself. In other words, the given time of arrival is the one moment of time at which it is impossible that any member of the party will arrive. Recipriversexclusons now play a vital part in many branches of maths, including statistics and accountancy and also form the basic equations used to engineer the Somebody Else's Problem field.

The third and most mysterious piece of non-absoluteness of all lies in the relationship between the number of items on the bill, the cost of each item, the number of people at the table, and what they are each prepared to pay for. (The number of people who have actually brought any money is only a sub-phenomenon in this field.)

The baffling discrepancies which used to occur at this point remained univestigated for centuries simply because no one took them seriously. They were at the time put down to such things as politeness, rudeness, meanness, flashness, tiredness, emotionality, or the lateness of the hour, and completely forgotten about on the following morning. They were never tested under laboratory conditions, of course, because they never occured in laboratories - not in reputable laboratories at least.

And so it was only with the advent of pocket computers that the startling truth became finally apparent, and it was this:

Numbers written on restaurant bills within the confines of restaurants do not follow the same mathematical laws as numbers written on any other pieces of paper in any other parts of the Universe.

This single fact fact took the scientific world by storm. It completely revolutionized it. So many mathematical conferences got held in such good restaurants that many of the finest minds of a generation died of obesity and heart failure and the science of maths was put back by years.

Oh, and they have made it available in 5:1 audio on the website - and jolly good it sounds!