He eyes her; her face is stony, adamant. "Off," she orders.
He demurs. He wriggles. He wheedles. He uses every Slytherin tactic he can think of. All of them fail against stolid Gryffindorism and the undeniable fact that he voluntarily consented to this course of action. That he hadn't anticipated this outcome is his own fault. With a grimace, he stands, and his hands reach for the waistband of his underwear.
Hermione hides a grin behind her robe's sleeve; Severus has no idea that he agreed to play strip poker with someone who has a master's touch in bottom dealing.*
*Bottom dealing is a method of card manipulation used to cheat, particularly at poker. The double entendre took a few minutes after I'd chosen the method to occur to me.