「……それ誰？」
「ワ、ワタシに決まってんジャﾝ」
「……ヘタ」

壁の文字はそれぞれ「おはよう」「こんばんは」です。

"......who's that?"
"It, it's me, obviously!!"
"......that's terrible"

The writing on the wall are their ways of saying "Good morning" and "good evening".