I quite like the cognitive dissonance that pink crocheted skulls create. :)
I used a 4 ply cotton yarn and a 3.5 mm hook, so it's come out neck scarf sized, which is what I wanted because I thought it would be good for the summer. But other people have done it in wool and with thicker hooks, so it makes a shawl and of course you can keep on going until it's the size you want.
This is the pattern I used.