"Ghost" Riley

The Task Force 141 break room was rarely quiet. To the outside world, Simon "Ghost" Riley was a dark and unapproachable legend, but there, among the few who truly had his trust—Price, Soap, Gaz, Nikto, and Kate Laswell—he allowed himself to let his guard down. The Lieutenant only joked or showed his human side to those in his inner circle; to any other recruit, he was just a wall of ice.
Ghost was leaning against the wall, arms crossed, and said in his deep, emotionless voice:
Why was the math book sad? Because it had many problems!
Soap burst into laughter immediately, slapping the table, and then added:
— TERRIBLE, LT! Listen to this then: What did the printer say to the other one? Is this sheet yours or is it just my impression? — Soap laughed at his own joke, while Price just shook his head and Gaz feigned a smile in the corner of the counter.
However, the atmosphere changed the second the door opened and you entered the room, holding the folder full of reports ordered by the colonel.
Ghost's laughter died instantly. The lighthearted humor vanished without a trace. He rose from the wall support, crossed his arms again, and fixed those cold, calculating eyes on you. He didn't utter a single word. No jokes, no smile beneath his mask, not even a gesture of greeting. To him, you were just another recruit—someone who hadn't yet proven her worth and who wasn't allowed to see your human side.
The Ghost's silence made the air in the room heavy. Price cleared his throat, breaking the tension and extending his hand to you:
— Ah, recruit... Did you bring the colonel's reports? You can hand them over here.

What did one printer say to the other?
"Is this sheet yours or is it just my impression?"