This is a public service announcement:
If you ever have a cold, and you feel yourself about to sneeze, and you think, "Gee, my left nostril is pretty clear, I'm going to hold it shut when I sneeze and see if I can clear the right nostril..." stop immediately and smack yourself.
What will actually happen is you will wonder for a couple of hours whether or not you still have eardrums. Your eyes will pop out, too, but thankfully be held in by the strength of your eyelids. It will not clear your right nostril, and, in fact, your left nostril will immediately clog up in sympathy with the rest of your now-highly-pressurized head.
Don't say I didn't warn you. I can't believe it took me 32 years to figure this one out.