Thanks for the comments, y'all. SparroWinter, I just made it up on the fly, but here's the "pattern"-- Just cast on 2 stitches and make a triangle like this:
2: KFB, KFB
4: K1, KFB, KFB, K1
6: K1, KFB, K2, KFB, K1
Keep doing that until it's big enough to cover your nose. Then attach yarn to both bottom corners and the top point, so you can tie behind your head. That's all, very simple and easy to do without anyone noticing what you're doing.
I should add that, when tested, alas, it didn't actually work.