Prisoners improvising weapons out of everyday objects like sociopathic MacGyvers are a staple of every movie that takes place inside a prison. However, real inmates aren't limited to just the sharpened toothbrushes and Nicolas Cage fleshmasks Hollywood gives them credit for.
Some prisoners melt down chocolate bars and throw the boiling hot confection over their enemies, which sticks like napalm and causes severe burns. We figure this must have been an idea the killer from Se7en kicked around during his gluttony planning phase.
At least you'll be a delicious burn victim.
8Chair Leg Nunchucks
Lorenzo Pollard built a pair of nunchucks in his cell out of bedsheets and a chair. Like Michelangelo imprisoned for accidentally killing a stripper on Donatello's birthday, he beat the hell out of a dozen guards and vaulted the prison walls to freedom (although he was quickly recaptured, which was decidedly less radical).