tgstation/-tg-station — pull request #946 by Glandouze (2013-07-09 20:22:46+00:00)
Title: Fixed two exploits with the biogenerator and the condi/chemmaster

You could use a negative value to get a lot, lot of stuff, needless to say that with infinite plasma and doctor's delight, you could break the game in no time.
http://puu.sh/3xgxC
http://puu.sh/3xhxD

Oh also cheese.
http://puu.sh/3xT3y