I've always thought the best 'accidental on purpose nudity' is when the target woman is in your house, and you have plausible deniability to 'not realize she was there'... you go waltzing around naked, round the corner and bump into her!! or be naked in the kitchen/living room when she (and your wife) are out shopping but you know they'll be coming home... its also helpful to have some airpods in your ears so you are 'listening to music' as you're walking around naked and didnt hear her car pull up or the front door open... of course this isnt just limited to a sister-in-law, but can be used anytime you know your wife or girlfriend's (hot) girlfriend is coming over or a pretty neighbor ENJOY!!!! and let us know how it went