My twin brother and I got an apartment together shortly after we turned 18. When our little sister Mary turned 18 a year and a half later, she still lived at our parents' place, though she began hanging out at our place many hours of the day and night since it wasn't out in the middle of nowhere. She kept some clothes there, and several of her friends began hanging out there as well.
An apartment full of teenage girls that just graduated from high school and had a tendency to leave the kitchen and living room very messy can be rather annoying. On the other hand, an apartment full of teenage girls that just graduated from high school presents many visual treats. Especially when the apartment complex has a pool and the apartment only has a small air conditioning unit, just powerful enough to stave off heat stroke on a hot day, it didn't really get comfortable inside on the hottest days of summer. So there was plenty of eye candy using our bathroom as a changing room before heading out to the pool in skimpy bikinis.
Some days, my sister had almost a dozen friends over, and I was almost constantly erect from all the delectable female flesh walking around. Judging by the look on my brother's face, and the way he shifted in his chair, I suspect he was as well. My sister was a cheerleader in high school, and was still friends with many of her squad mates. I was in the marching band, and got to know some of them from working together for pep rallies or at school sports events.
Most often, it was just my sister's two best friends, in addition to her. Janet was about 5'2", a very petite blonde with perky little breasts and an ass that could give a statue an erection. Janet was the one they threw high into the air at football games, and I think she sometimes forgot to wear anything under her little skirt, at least it looked like that from my seat in the band section at the games.
Sarah was a tall blonde, 5'10", with legs that seemed to go on forever. The kind of legs you could suck on for days. She had good sized breasts, and seemed to dislike wearing bras, since her nipples were often noticeably through her tops.
My sister was the hottest girl at school, and I don't feel any shame admitting that during high school, visions of her sent as many loads of jizz into a towel or down the shower drain as all the other girls at school combined. 5'5", long dark brown hair, spectacular C cup tits (I checked the size on her bra while pulling her laundry out of the dryer recently), with perfectly sculpted legs and ass. Mary ran a lot to keep in shape, and could have been on the varsity track team, if she wasn't so busy with cheerleading.