I had a threesome with my buddy's fiance and her best friend. While friend rode me cowgirl, old mates missus reached under her friend and grabbed my balls and squeezed as hard as she could.

I fucken yelped and yanked her away and she explained that because her fiance liked having his balls squeezed and we were friends we might both like it. I got better after a few minutes and we continued without the CBT.

They broke up later because friend couldn't keep her mouth shut, and it caused a big rift in the friend group. It was a mistake desu, but it was still great at the time.