Football: I also will go along with winning 5 SBs as a QB for the Cowboys.
Basketball: Breaking Wilt Chamberlain's stats from the 1961/62 season: 50.4 points per game average, 25.7 rebounds, 48.53 minutes per game, and 100 points in a game. Far and away the most dominant single season by any player in any sport.
Baseball: I'll go with Aaron's home run record. Home runs are the only exciting aspect of the "pastime".
Beach Volleyball: Karch Kiraly's winning a title at age 47 (last season). What I wouldn't give to be in that kind of shape. Karch is only a couple of months younger than me and I played against him and Sinjin Smith nearly 30 years ago. He is still playing at a high level while I am struggling to fit into my shorts. I also played against Wilt in a beach tournament which was truly a thrill for me since he was one of my childhood heroes.