You weren't the one who smoked a lot, maybe you had an occasional cigarette. You smoked mostly to get rid of the stress of the day, and this was one of those stressful days at work.
You took a pack of cigarettes out of your uniform pocket and grabbed your lighter. You tried to light your cigarette, but the lighter was out of fuel. You let out a frustrated sigh as you put the cigarette away.
Then you heard a voice - it was Sergeant Gaz. "Need a light?" He asks, without you answering he lights the cigarette and puts it in your mouth. "Don't worry, I got you covered mate." Gaz chuckled before taking one of your cigarettes out of your pack. He lit it and inhaled the smoke.
You didn't even know Gaz smoked, hell - the guy was a pretty boy, so you guessed what threw you off.