When me and my ex-girlfriend had been together for just a few weeks, she invited me over to her parents house. Her parents weren't home at the time (they were on vacation) and she was staying at their place to take care of the plants and the cat. So I drove to her parents house and I rang the bell. Her younger sister, dressed in casual summer clothes, opened the door and invited me in.
We walked through the house to the garden and I saw my girlfriend wearing a bikini.
She was fastening her bikini top, so that meant she was topless just before I came in.
This already was a huge turn on. You have to know: typical Dutch gardens are tiny and offer very little privacy.
See the pictures I've included for an example. Her parents garden was similar (but better looking) and offered just as little privacy.
These days it's very rare for women to be topless in the backyard. Especially for young women (my girlfriend was 20 at the time).
So we talked for a while and she got me something to drink and after a short while she asked me if I had any objections if she went topless. Obviously I didn't have any objections. So she removed her top and revealed her very nice breasts. Her sister and her were chatting along like nothing unusual had happened, while I was trying to hide a giant boner.
About fifteen minutes later the doorbell rang. It was the boyfriend of my girlfriends sister coming to pick her up. He was a bit older than us, I think he was about 10 years older than her sister (who was 18 at the time). So we talked for a few minutes in the garden. Three fully dressed people (me, her sister, and her sisters boyfriend) while my girlfriend was only wearing a tiny bikini bottom, in a garden with very little privacy. She did try to cover her breasts with one arm.
After her sister had left she again got me something to drink. She stayed topless this time and covered her breasts with her hands while she walked to the kitchen. When she returned she held one drink in her left hand and another drink in her right hand, while her uncovered breasts were nicely bouncing and wobbling with each step she took. It was a huge turn on! A few minutes later we went upstairs to have sex!