You'll need:

  • A watermelon. (Preferably not square, because they're harder to hollow, not to mention damned expensive for making psuedo-moonshine that will probably destroy you.)
  • A big shiny fuck-off knife.
  • A spoon.
  • A bowl.
  • 1 Kilogram of sugar. (2.204622622 pounds my converter reliably informs me.)
  • A bunch of yeast.
  • A large pan.
  • A funnel.
  • A fridge
Take your watermelon and using your big-shiny-fuck-off knife, cut a hole in the top, remembering to keep the piece you cut out. Scoop out all the middle with the spoon and chuck it into the bowl with the sugar. Put in the yeast for good measure. Stir it up some and bung it all back into the watermelon. Replace the lid bit, then wrap it all in cling film and put it it under your bed or something. Anywhere it's relatively warm but not above 40° celsius will do. (You really don't want to kill the yeast and just end up with a mouldy watermelon in your airing cupboard.)

Leave it for about a month or two, then unwrap it. Take all the gunge back out, put in the big big pan and boil it all up. (If you're really desperate, you could probably eat it now. But it will probably taste foul. And then kill you.) With your funnel (Not a metal one for christ's sake, unless you want to have no hands left.) catch the vapour that comes off. You'll probably want to stop collecting it when the vapour goes a bit misty, for the reason that the misty stuff is methanol and will make you go horribly blind. Which I'm assuming you don't want. (However it'll probably make good firelighter for the thrifty, or perhaps alternative car fuel.) Put the vapour in a container of some kind then stick it in the fridge. It will condense to almost pure ethanol. Serve to someone you don't like, or when your parties really need a kick-start.