The sixth, seventh or first night of the week, depending on your religion.
Saturday night is the most important invention in human history. Saturday night is the reason most conflicts have been resolved and is responsible for some of mankinds most excellent discoveries.
Acceptable ways to spend Saturday night include going out to the cinema, drinking beer, watching the footy highlights with your mates, clubbing, eating kebab, beating the wife and/or kids, and spending a dirty night out. Unacceptable ways to spend a Saturday night include going to bed early and being ill.
Without Saturday night it is conceivable that the couple of protein strands that joined in the primodial goo to form Earths first ever life form would never have done so, and all life as we know it would not exist.
Several other good facts about Saturday night include that it's impossible to fail to pull a slapper
, it's the only night apart from Wednesday that it's legal to dine in an Indian restaurant, it's my favourite night of the week and it follows Friday night.