Despite being a Proper Grown-up with my own business & TaxWeasels* I can't resist a Yo Momma joke.

Ahem. Anyway, tomorrow is our monthly knitting club at the tearoom, The Social Knitwork (name courtesy of the every pun-tastic Mike). It's a friendly, easy-going bunch of people, there's no charge for attending, and no one will look at you funny if you're making something crackerarsed like a 
Lucha Libre balaclava or 
Giant Squid Hat (mostly because I love that sort of thing)
So, to celebrate, here's my pattern for a really easy rolll-brim hat. Not 
only is it easy, it's also fast (insert appropriate 'Your Momma' joke 
here), and only takes an evening to make (this particular hat took me a 
Sunday double bill of Columbo). It also has the magic power of fitting 
comfortably on different sized heads, from my own 21" scalp to 
Mikeyfox's Mekonesque 24" cranium. 
You
 will be needing a 41cm/16" 8mm circular needle (the 8mm is the needle 
thickness, the 41cm/16" is the length of the circular needle). Don't be 
afraid of the circular needle, it's more scared of you than you are of 
it. You'll also need 4 dpns (double pointed 
needles). Yes, they are scary looking, and if you don't keep an eye on 
them they'll slip down the back of the sofa & perform acupuncture on
 you when you're watching old episodes of QI on Dave. 

You'll
 need a ball of wool too, the chunkier the better. A single 100g ball 
should do the job (though you won't have anything left over. If you're 
worried, get more, it'll get used for something eventually). I used King
 Cole Homespun super chunky yarn in green, which is a nice thick 
wool/acrylic mix. You could use any chunky wool suitable for an 8mm 
needle, Sirdar Super Nova Tweed wool works really well too. (If you're 
really worried about the finished hat size, then knit yourself a gauge 
& work out the stitches per inch)
 
Cast
 60 stitches onto your circular needles. Yes, it looks far too small 
right now, but it will work, I promise. Now comes the fun 
part, 'knitting in the round'. Yup, you're going to be going around in 
circles. Firstly straighten out all your stitches & make sure 
that they are all pointing inwards (or down, if that's your thing). You 
don't want to get your stitches twisted up, or you'll end up knitting a 
Mobius strip (a surface with only one side it may be, a hat it isn't). 
You'll need a stitch marker (Plenty of people buy stitch markers, they 
come in all sorts of shapes & colours. A paperclip works just as 
well. For this I'm using an Ankh ring sent 
to me by the lovely Cynthia as my stitch marker). Just slip it onto the 
needle next to the last cast on stitch. The stitch marker is just there 
to show you where the end of the row is. When you knit your row & 
get to it, you just slip it from one needle to the other & carry on 
knitting. It doesn't get knitted into the hat, just goes round & 
round the needles and helps you keep track of where your row 
starts/ends. 
Hold the needle with the last cast on stitch in your right hand & the needle with the first
 cast on stitch in your left hand and knit into that first cast on 
stitch, pulling the yarn firmly to prevent getting a gap in the join 
between the two stitches (though this being a roll brim hat, no one will
 actually notice if the joint is a bit shoddy). 
Sensible folk
 will recommend that you knit with the needles facing towards you, 
rather than away from you (like in regular knitting). I can't wrap my 
head around such things, so I knit with needles towards me, which has the 
bizarre effect of turning the hat inside out. But that's fine, just turn
 it right way round when you're finished. Work whatever method suits you
 best.
Another
 magic power of the circular needle is it turns a Garter stitch into a 
Stockinette. Why does it do this? Because 
you're knitting in a spiral, rather than the back & forth of regular
 needles. So if you want to make a garter stitch hat, you'll need to 
knit 1 round, purl 1 round & keep repeating. Or you can knit an 
inside-out, garter-that-becomes-stockinette magic-hat instead. Keep 
knitting until you have 6" or 7" or so of knitting (a little less if 
you're making a Beanie style hat, a little more if you want a big chunky
 brim).

Now comes the decreasing. Just relax. get yourself a cup of tea.
 Or a glass of wine. Who am I kidding, get a bottle of wine. Knit 8 stitches, 
then knit 2 stitches together. Repeat until the end of the row. Now knit
 7 stitches, and knit 2 together, and repeat until the end of the row. 
Now knit 7 stitches, and knit 2 together, repeat to the end of the row. 
I'm sure you can see where this is going. At this point you & the circular needles will have to part ways. Yes, its time to 
meet the dpns, the double pointed needles -discovered by a the Mad Arab 
Abdul Alhazred in the ruins of Babylon & used to knit a cabled tote 
bag for his early draft of the Necronomicon. Wield them and despair!
Okay, so they're not that bad. But look, they make an Anarchy symbol when used to knit a hat. Coincidence? Probably. 
You
 can just slip your stitches onto 3 of the dpns, spread them out equally
 & continue knitting the rounds of decreases. Or you can knit 
straight onto them, whatever works best for you. With the 4th needle 
knit off the dpns (it sounds complicated, but it isn't. Just take your 
empty needle in your right hand & the dpn with the stitches you need
 to decrease next in your left. Knit & decrease from left to right, 
and use the now empty left hand dpn to do the same again to the next 
one). Knit & decrease for as long as you can stand to (I keep going 
until I have 3 or 4 stitches, but I'm Peculiar), cut your yarn, leaving a
 tail of several inches, and thread through the remaining stitches. Tie 
off & weave in any loose yarn left (don't forget the bit at the brim
 where you cast on). Turn it right way around (if you've been knitting 
it inside out)

There you have it. A very fine hat.
You can play around with the pattern. If roll-brim isn't your thing, then a rib stitch for the first couple of inches works well, and gives it a bit of elasticity, too. 
And finally...
Yo Mama is so fat she has mass whether the Higgs Boson exists or not! 
*Although the TaxWeasels have been fired and replaced with a much nicer lady called Diane who doesn't spend all her time coming up with new ways of screwing me for more money