Ingredients (why do people use the term ingredients? I'm not saying a t-shirt isn't edible, but still...):
*a pair of scissors
Cut your hem off. Now cut off the shirt under the armpits, so you have one large tube. Pull it over your head, and then loop it around again. Ta-da! A nice soft scarf that will gain many compliments and keep your neck warm. Or you can drape it around your shoulders and pull it up like a hood.
Disclaimer: if you do the hood idea, it's not my fault if it looks hideous. I tried it and it looked funky, but it might be because it was crooked and too short for a hood.