I think I've finally managed it.
Knitted in Woolly Bully, colour #256, on US10 needles. I used one skein.
I'm still deciding if I want to add something to the ends of the horns -- small bells might be 'proper', but the annoyance factor might be too high. Any suggestions?
A picture of the lumpenjesterhat looking very sad and lumpen indeed. I shall have to wear it at all times in order to keep it happy and perky. Woe is me. ;)
The pattern, such as it is, follows:
1. Cast on 60 stitches. (I used a cable cast-on.)
2. Knit in the round for 20 rows. (*)
3. Decide how many tails/horns you want. Place markers where you want horns to be.
4. Continue knitting in the round, doing paired increases on either side of the markers each round, until the horns are of desired size. (At final count, I had 120 stitches on my needles.)
5. Bind off from each tip of horn to the center of the hat. (I used a three-needle bind-off.)
6. Enjoy your hat.
(*) : If I knit up another one of these hats -- I'm now tempted to get a US10 circ with a much longer cord, and try an eight- or ten-tailed hat -- I would only knit 15 rows before starting the increases. I've rolled up more of the brim than I was intending to. If I was going to add a trim at the bottom instead of making a rolled brim, I would only knit 10 rows before starting the increases.
Also, if doing a hat with more than three horns, I think I'd recommend binding off with grafting/Kitchener stitch, in order to reduce the bulk at the middle.
Enjoy. :) I'll answer any questions about the hat as best I can.