Adrenaline spike, I guess, should be a medical term, what does it imply here? Does it mean Chris was nervous? Does "on the cigarette-wagon" mean sb is in a dangerous situation? Chris felt an adrenaline spike, and not for the first time in the last few days cursed the fact that he was on the cigarette-wagon. He reached out for a piece of chewing gum from the bedside table. If there had been a packet of cigarettes within reach, it would have been game over for this year's attempt to quit.