This phenomenon is known as peer pressure. Peer pressure happens when the desire to be like somebody else just to fit in happens or simply to fit in. In here, if you are originally not a cigarette smoker but being around with people who smoke makes you want to smoke too, then you are subject to pressure. Because you will feel left alone or not in the loop if you do not become one of them, to follow what they usually do and this will force you to do it, to smoke even though, deep down, you know that it is wrong. You just disregard the fact that what they are doing is wrong and you just want to do it because everybody is doing it.
