You made a mistake - a bad, bad mistake. One that would reveal your perverted secret to your wife. She stood in front of you, a devilish, mischievous smile on her face, and your step-daughter's flower printed panties in her hands. She knew.
"I know perversion when I see it..." Nikki said pressing the panties against her face and sniffing them, "when I smell it. Are you sick like that, sweetheart? Is that what it is? Am I just not cutting it for you? Do I need to put the schoolgirl skirts back on?"
Of course you were going to deny that anything ever happened - it was only natural to do so. You'd come up with bizarre excuses as to how and why those panties got into your suitcase, and your wife wouldn't believe any of them - she knew the truth.