Let me give you a hint: it looks like this!
Yes, that's right. A cigarette really should be known by its more common name, a firestick. Both of my boys have seen these laying on the ground and have inquired as to what they are. I don't think I have ever given them a name, and I have certainly not called them a firestick. I've always explained that people put them in their mouths and they are really bad for you and they stink and are disgusting. If I start early, maybe they will never try them, right?
Though the thought has crossed my mind that we will encounter someone smoking one and my boys will exuberantly exclaim, "Eeeww! That's disgusting!" Maybe I should be embarrassed, or maybe not. After all, they are telling the truth.