I've never had one, but my friend got one a couple weeks ago. He was riding a skateboard, holding onto the back of his friends car, doing about 30mph. He shouted to the driver to slow down but the driver slammed on the brakes and my friend went down headfirst. No helmet. He was in the hospital for a few hours but they released him that same night -- today, he still has difficulty balancing, memory problems, and can't taste or smell anything. The doctors said that if these problems didn't correct themselves within a month, they may be permanent. Scary stuff, but it's a miracle the kid is still alive. Don't be stupid with a skateboard.

Another friend of mine flipped his truck a month or two ago and got a concussion too, but his injuries seem to be much more minor. Though he was definitely "out of it" in the weeks after the accident. From these two cases, my only real familiarity with concussions, I'd venture to say that a concussion is a pretty major thing. You'd probably know if you had one. My guess, anyway.

-useless"And I don't plan on EVER getting one"ness