What if you lie about whether or not you smoke cigarettes on your health insurance application?

The answer will depend greatly on what type of health insuance you applied for and in what state. Here in CA if you lied on an application for individual insurance then the penalty can be severe. If the insurance company can demonstrate that they would have made a different underwriting decision if they had all the facts then they will unwind the policy. Basically they would say you never had coverage and return your premiums to you less any benefits paid. If benefits paid exceeded the premiums paid you would owe that money back to the insurance company.