This is based on the video game called Trauma Team.
In the game, Gabriel Cunningham is a pretty heavy smoker, almost always seen with a cig in his mouth - but since he's a doctor, his cigs aren't lit until he's outside. So, after the events in the game, Gabe decides to try quitting smoking, and asks his best friend, Hank Freebird, to help him. He's badly craving a cig and tells Hank he's headed home, but really he's in the park, smoking that "one last cig". Hank, while heading home himself, happens to catch Gabe in the park. Hank has a gentle nature and he really does care about his friends like they're his family, and he doesn't like being lied to. It hurt him to see this.