When my wife's younger sister was having a new bathroom installed, she came over to our place for a shower each day for about a week. This was about four years ago, just before Covid.
We have a spare bedroom and ensuite bathroom on the ground floor (for my wife's disabled parents when they visit). We let her sister use this room so she could leave all her toiletries and towels and stuff there, rather than carting it back and forth.
On the first day she came over for her shower, I took the rubbish out, walked past the bedroom widow, and could see straight in between the venetian blinds. The light was on, and it was dusk outside. She was bending over, drying her hair with a towel. I got to see her breasts dangling beneath her (they were small, but a quite saggy, with surprising big areola and nipples). I wanted to see her straighten up so I could see her pussy, but i was paranoid that my wife would wonder where I'd got to, so I reluctantly bunged the rubbish in the wheelie bin, then went back indoors.
I was gutted, but my wife actually saved the day - she pointed out some rubbish that I'd missed, so I took it out, peered in the bedroom window again, and was rewarded with her sister's pussy - a quick glimpse of her full puckered labia protruding from a neatly trimmed bush
I've never really gotten on with her sister that much, but I had a newfound respect for her after seeing her naked that day. Unfortunately, although she came over several more times that week, I had to go away for work, so I didn't get to perve on her again.