LOOK, she doesn't get many chances to laugh these days, Shiro, let her have this!

"O-oh no!" See, she feels for him, never mined the barely-held-back chortling. "Those are always the worst, I do not envy you at all...!"

And she means it, she doesn't envy him. ... That doesn't mean she can't be amused by him while she's at it. =)