In college, I wanted to test my resolve for addiction, so I started smoking a pack a day for six months. The idea was to see how hard it is to quit so that I could better understand what people go through. Never took, though. Every cigarette was gross to me from the first one down to my last day. I threw away the box on the last day and never had a single moment where I wanted another one.

Instead of learning about addiction, it taught me a ton about socializing. Sharing a cigarette with a romantic interest is such a low friction way to be able to keep close enough to have a conversation, and subtly reinforce intimacy. And after I quit, I would bring a pack to any party I went to and not tell anybody until someone was asking. There was a double whammy of providing one for a stranger, and saving a friend from having to donate one.

By the end of the night, when everybody was either trying to bum one or find someone sober enough to make a run to the gas station, my reputation for both having cigarettes and not smoking made me pretty popular. It was also really nice that when people praised me for it (mildly; "that's really cool of you, man") my stock response was "yeah, no worries. I know how great it would be if someone had a Dr pepper for me when I was dry", which made a lot of people offer me my favorite soda all the time.

I still can't stand smoking, and have only had a dozen or so in the decade since then, strictly for ingratiating myself to people. But there is nothing out there like cigarettes for socializing. I'm with a lot of other commenters here in wondering how much we've lost by stigmatizing it without ever reconciling with the (trivial, in comparison) benefits.