To my knowledge, the biggest my wife ever had. She had been a shared wife for a couple years (1 local and 2 distant fuck buddies, all friends of mine), and we were in a "distant" buddy's hot tub at his house. We had teased about fucking earlier that day, and now it was late in the evening...
We were in his hot tub and she asked, "Are we going to fuck?" She was on her period, so I said, "Well, that's up to you". She said I can take care of that and removed her tampon, then moved across the tub over to my buddy as he laid back in the hot water.
She was in front of him, presumably between his legs, and she started to stroke his above average cock (8-9" maybe?) underwater, got him hard, and he lifted his hips out of the water.
She then straddled his cock, and with just the fingertips of her right hand, she lined him up to her wet opening. As she lowered and wiggled herself onto him, she moaned a few telltale "Mmmmmm" sounds until he was all the way in.
I asked her, "How does that feel?". She said, "Ohhhhhhh, he's really filling me up".
I watched her ride him slowly, and it seemed only a few minutes went by and I could hear him begin to grunt as he filled her with his cum. She repeated her "Mmmmmm", and stayed on him 'til he went soft.
JR
Hubby of Hotwife from Spring '89 to Winter '93