Any D.A.R.E. officer worth his salt loves to emphasize the dangers of peer pressure. As long as there have been drug-prevention programs, there has been an increased awareness of how susceptible we all are to social influences. This can be particularly true of smoking. Our friends, colleagues and family members are who we pick up social cues from, sometimes learning habits and behaviors very early on. Besides that, social occasions can be stressful or celebratory -- both triggers for smoking.
Even if no one else in the group is smoking, many folks are conditioned to think of a social space as a spot to relax and enjoy a cigarette or cigar.