He had made her take off her grey skirt, of course, there in her classroom, but getting Mary's bottom nice and red before he bared it completely was important to him. Mary needed to feel that David, as her husband, had the right to spank her any way he wished, if he should decide that she needed to feel his firm hand.
And anywhere--for example, in her own classroom, when he found her there grading papers when she had promised to be home to get ready for the party.
David couldn't deny that to make Mary bend over a student's chair and present her naughty rump for punishment in the polka-dot panties he liked so much took some of his anger away. He still had enough left, though, that he wanted to make sure she remembered this spanking. As he took down the polka-dot panties he watched Mary kick her foot and heard her whimper in shame and fear at the thought that she would now have the rest of her spanking on the bare.
"Please, David," she said, "I've had enough. I'm sorry. Please don't take down my panties."
"I think not, darling," David said. "I'll take down your panties when I choose."