Navy (colour)
Navy is a blue so dark it is regularly mistaken for black, usually at 7 a.m. while choosing socks.
Turquoise
Ask two people whether turquoise is blue or green and you will get three answers and one person leaving.
Magenta
Magenta has no wavelength of its own; the brain makes it up, and nobody has had the heart to tell it.
Off-white
Off-white is white that has been switched off, or at least turned down a little to save energy.
Gold
Gold is yellow that has been promoted, and is valuable mostly because nobody can make it in the kitchen.
Silver
Silver is grey that has been polished until it believes it is worth more.
Tulip mania
In 1637 some Dutch tulip bulbs reportedly sold for as much as a house, then prices suddenly collapsed.
Traffic light
The first traffic light was installed in London in 1868, was gas-lit, and was worked by a policeman.
Black
Black is the colour of things that are black, and of everything else once the lights go off.
White
White contains every colour at once, which is why it is the only colour that has never been asked to choose.