Zoe thought that the YMCA part of her punishment was funny for being so random and vague. But she was smirking more at the previous comment about her father.

Mother

What do you think is funny?

Zoe

I don't think it's funny—

Zoe should have stopped right there, but then she continued knowing full well that she shouldn't, that she was treading dangerous waters already and that this would be taking the plunge—

Zoe

—I just think it's kind of sad ... that you expect him to come home anytime soon. Or sober enough to take apart my computer. Isn't he cheating on you, anyway?

Slap.

It was a vicious, backhanded, very loud slap. Her mother swung so hard that she missed Zoe's cheek, landing squarely on her jaw instead. It surprised Zoe more than it hurt her, though after a few moments it started to smart horribly and her lip felt numb. The girl stood there with her mouth open.

Mother

Get out of my sight.