SCA member and Darwin Awards author Wendy Northcutt shares several tales of "Medieval Mayhem" on the Darwin Awards website.
The webpage discusses less-than-bright behavior at a recent Pennsic War.
From the website:
The saying goes, fighters have two neurons, one is lost and the other is out looking for it. A knight fell "dead" (i.e., passed out) on the battlefield after a minor body blow. When he came to, it was revealed his appendix had been removed just last weekend, and he was still "stapled shut" from surgery. Please, hide your knight's helmet if he intends to endanger himself. Protect your fighters!