You bet. I just came across this on some post from some random thread the other day on BF:
http://youtube.com/watch?v=cUi2wvzZyfk
The part where he makes a whistle is the second half. I was able to make a very good one on my second try. It works extremely well, though not extremely durable if have to keep bending it into shape. I've been carrying around one made from a MGD can for a few days. Very easy to do one handed. I thought it was a neat backup option.