11 poisen pills one's an aspirin and it weighs different. Anyone heard this riddle? can ya help me out?

[zmanrebqb]

You are in a king's dungeon and given one chance to survive. He gives you twelve pills. 11 are lethal, one is only an aspirin. The aspirin weighs different than the other pills (not given whether it weighs more or less). He gives you a scale. The kind that teter-totters, but you can only use it three times. How do you survive?

[C M]

You don't take any of the pills.