A mysterious matter of trust

"When you said lunch I expected something more… elaborate. Are you sure just a sandwich from the canteen is good enough?" 

"Yes, it's alright." Ji-Su grinned. 

Then, at Su-Jin's look of doubt he added with a light shrug. 

"I've had a late breakfast."

Su-Jin clicked her tongue, staring blankly at the sandwich she held in her hands. A moment later, she turned her head and shot the man sitting next to her a side-glance.

"You did me a huge favor by finding my employee ID card. I don't even want to think about the hassle I would have had to go through if I really lost it."

"It was my pleasure. Besides, it also provided me with a bit of entertainment this morning, so it was my win as well." 

"Entertainment?" Su-Jin widened her eyes. "What could my ID card do to entertain you?

"You don't need to know that." Ji-Su chuckled mysteriously.