"Intelligence is the ability to reconcile totally contradictory situations without going completely bonkers. For example, having a stomach ache and not having a stomach ache at the same time, holding a hole without the doughnut, having good luck and bad luck simultaneously, or seeing a real estate agent waive his fee."
The way it functions is very interesting. When the Drink button is pressed it makes an instant but highly detailed examination of the subject's taste buds, a spectroscopic analysis of the subject's metabolism and then sends tiny experimental signals down the neural pathways to the taste centers of the subject's brain to see what is likely to be well received.
However, no one knew quite why it does this because it then invariably delivers a cupful of liquid that is almost, but not quite, entirely unlike tea.
The Nutri-Matic was designed and manufactured by the Sirius Cybernetics Corporation whose complaints department now covers all the major land masses of the first three planets in the Sirius Tau Star system.
"Your Plastic Pal Who's Fun To Be With."- from the marketing division of the Sirius Cybernetics Corporation.
The motto stands - or rather stood - in three mile high illuminated letters near the Complaints Department spaceport on Eadrax. Unfortunately its weight was such that shortly after it was erected, the ground beneath the letters caved in and they dropped for nearly half their length through the offices of many talented young complaints executives - now deceased.
The protruding upper halves of the letters now appear, in the local language, to read "Go stick your head in a pig", and are no longer illuminated, except at times of special celebration.
In other words - and this is the rock solid principle on which the whole of the Corporation's Galaxy-wide success is founded - their fundamental design flaws are completely hidden by their superficial design flaws.
The above texts are excerpts from the Hitch hikers guide to the galaxy