What's so funny about this?

hat are you looking at me for Are you going to eat""You eat first," Gu Nanci said, picked up a tissue and handed it to her, gesturing, "Wipe it."Su Han took the tissue and wiped his lips casually, the... back, trying to avoid his touch.As he stepped back, his foot slipped on the stairs. He lost his balance and fell backward uncontrollably."Ah!" Su Han was startled, her eyes widening as she reached ou...