It's just a continuation of how he knocked himself out of the presidential race in 2007.......

"WASHINGTON — Delaware Sen. Joseph Biden spent his first official day as a 2008 presidential candidate defending his description of likely Democratic competitor Barack Obama as the "first mainstream African-American who is articulate and bright and clean and a nice-looking guy."
Biden burned by 'clean' language - USATODAY.com
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Those two brain aneurysms he's had have done some major damage......

"Biden's brush with death came two decades ago, just months after he gave up his own campaign for president. Biden, who had suffered headaches for weeks, found himself with a headache so severe that he lay down in a fetal position, then passed out for five hours. Upon awakening, he made it to a hospital, where doctors discovered a ruptured aneurysm -- a condition so severe that a priest said he was called in to administer the last rites.

A brain aneurysm is a bulging blood vessel, which occurs when a spot in the vessel weakens and blood pressure forces it out like a balloon. A ruptured aneurysm is generally extremely painful -- many doctors say it is typically the most painful headache you'll ever experience.

About half of all ruptured aneurysms prove fatal, and many others lead to lifelong disability. Neurosurgeons at Walter Reed Hospital were able to save Biden's life by putting a metal clip on the artery to stop the bleeding. Biden also survived a blood clot that lodged in his lung as he recuperated.

Through screening, a second aneurysm was discovered a few months later and surgically removed before it burst."

Democratic VP nominee Biden releases medical records - CNN