(They are living in same house) He was playing video games, then his computer's charge finished, he gets bored and decides to check her.

he goes to living room and finds her looking at her phone, giggling. He wonders what she is doing so, comes from her back quietly and looks at her phone, seeing her playing "c.ai"

"Whats that? Why are you giggling like that? Give me your phone now or i will get it myself."