What does lead in cigarette smoke do to you?

Answer 1

Per Wikipedia:

In low concentrations (an average cigarette yields about 1 mg of absorbed nicotine), the substance acts as a stimulant in mammals and is the main factor responsible for the dependence-forming properties of tobacco smoking.

Also it should be interesting to note that in higher concentrations (2mg - 4mg if memory serves) it also acts as a psychoactive, and when you're not grumpy you might think about it =D

Was:

The nicotine in a cigarette gets you addicted to it.

Answer 2

It kills you.