Fun:Four
From RationalWiki
4 comes after three, and before six, but five comes first. In this way, these numbers form what is known by mathematicians as the first ordinal circle-jerk.
In the traditional incomprehensible Roman method of writing numbers, four is inscribed thus: IV, which is only useful if you need a quick rush from your drugs.
If you hear someone yell "4!", it means "duck!": it is not much clearer than "heads up!", which means "heads down!"
FOUR is PURPLE.
Or YELLOW depending on your SYNESTHESIA.
4 is also the number of double martinis it takes before the slob you're sitting next to at the bar actually starts to look halfway decent.