No Helmet? No Problem
When you're exposed to vacuum, the air in your lungs is forced out through your mouth. After that, you should be able to make breathing motions normally, but there will of course be no air to breathe. You will not experience any exploding eyeballs or embolisms like you see in the movies, although you may experience the Bends (this is when your blood boils). You'll also feel the spit on your tongue and sweat on your body boil away. It's described as a fizzy feeling, like drinking soda. Otherwise, you don't feel very much. Until you die of oxygen deprivation, that is. So there really isn't much you can do here, bad luck buddy.
