Good luck

In the same way that it is good luck to find a 4 leaf clover, in some countries it is good luck to witness a car crash, an event that you will not see many times in your life. Witnessing your own car crash however is not considered good luck though, for obvious reasons.

Yodaism

Yodaism is a speech impediment whereby the afflicted speaks like Yoda.

I've recently found out that some people actually want to speak like this!
http://www.yodaspeak.co.uk/index.php

...and it seems to be called Yodish.

Keyboard

If you press all the keys down on your PC keyboard at the same time you get a special character that no one has ever seen.

Baileys

It's impossible to drink more than a pint of Baileys.

Tea

Tea made with urine is colourless.

Eraser

You can't write on a pencil eraser with a pencil.

Cereal dust

The dust in the bottom of cereal packets is carcinogenic.

Bath plugs

Most peoples' bath plugs are attached to their bath by too much chain. If this surplus chain was removed and joined together then the chain would stretch over 3 times round the earth.

Headphones

Some people cannot wear in-ear headphones as this awakens a prehistoric fear that they have a newt crawling inside their ear.