Who is a chainsmoker?
The Chainsmokers is an American DJ/production duo, I think that is what you are referring to.
I was thinking it's referring to someone who is addicted to smoke, either cigeratte or marijuana
The Chainsmokers
The Chainsmokers are an American DJ and production duo consisting of Alexander "Alex" Pall and Andrew "Drew" Taggart. They started out by releasing remixes of songs by indie artists. The EDM-pop duo achieved a breakthrough with their 2014 song "#Selfie", which became a top twenty single in several countries. They have won a Grammy award, two American Music Awards, seven Billboard Music Awards and nine iHeartRadio Music Awards.According to Forbes 2019 list of highest paid celebrities, The Chainsmokers were
numerous sound effects including various alarms, a foghorn and machine gun noises are heard. Ed, the vault guard, asks "Halt! Who goes there?", and then an exchange is heard where Ed, apparently having been in the vault for a long time, asks "We win the war yet?" When Benny assures Ed that the war has been won, thinking that Benny was referring to World War I, Ed says: "Good. What do you think they'll do with the Kaiser?"