Her best friend.
I know this isnt original, but I have to tell someone. I was dating this girl who was chubby and sweet and we would get drunk alot in her room with her cop dad right next door. So one night we were drinking in her room with her best friend that came down from up north and she said she wanted to watch us have s**. My gf agreed to it as long as we had a blanket over us. She didnt join us that night or rub herself to us. But the next day my gf needed to work so I said I would hang out with her friend. We ended up walking around in the park forest and she started to kiss me. Then she got right down to her knees. I ended up f****** her on the dirt ground while some dude walked by watching us. Long story short I broke up with my gf and moved up north with this girl for a year where she would let me do a couple of her friends on the regular while she watched and join sometimes.