Best quick argument against the "social contract" canard

[ojc02]

I got to talking politics with some ppl at school the other day (very dangerous). They used the "social contract" argument. Apparently by participating in society I am signing a contract and therefore have to agree to do some things that they think are good for society.

I was shocked how many people nod their heads when they hear this crap. My problem is I need a good quick argument against it and I couldn't think of one. Best I came up with was that I never signed anything and a contract is supposed to be a voluntary agreement. I just got blank looks... Any ideas? Maybe I need a good analogy or a freaking puppet display or something.