There are probably three:
SU vs Houston, where if someone had said "Clyde Drexler will be one
of the greatest 50 players in NBA history", you'd say "Yup." And if the same
person had said "Hakeem Olajuwon will also be on that list", you'd have laughed.
SU vs Gtown in 1989.
SU vs UConn in 1994, where SU won 108-95, in a fantastic game.
Kev
This one. Don't think I've ever had more fun than the 108-95 game. Donyell Marshall was unstoppable, but Autry and Moten were better. Wallace had the late dunk and-one to clinch it.
Someone else mentioned the Kentucky game a couple weeks later. That was an underrated fun one, too. Again, Autry was stellar, the crowd was bonkers, and we beat another top-5 team.
Also:
Georgetown in '96 (Iverson got shut down and we won by 22),
Pittburgh in 2003,
Oklahoma in 2003 (honestly was an ugly game, but an awesome experience),
at West Virginia in 2010 (two top-10ish teams; can't think of a better place to win),
Connecticut in 2000 (after four years of "meh," electricity returned to the Dome; wild, wild night - could've beaten them by 40 if we'd kept our foot down; UConn from 1995 to 2000 was like what Georgetown had been to us ten years earlier...they'd just owned us),
Georgetown in 2012 - wasn't the prettiest game, but it was very loud and we did a good job covering for some mistakes by our underclassmen (exactly the opposite of the Georgetown loss the previous year); great shooting night for Joseph.
Indiana this year; I've never been more confident. We were just sitting at RFD grinning at Indiana fans in their silly pants before the game.
But not Wisconsin in 2012; absolutely not. March heat wave, was probably 90 degrees in the upper deck; horrible almost- gag job down the stretch; that last missed shot hung in the air for about a half hour and took ten years off my life. No.
[Also, I was neither there nor alive, but to the poster who mentioned the St. Valentine's Day massacre in the early '70s: yeah. I don't know anyone who was at that game who wouldn't list that in the top 3 or 5 games. Helped put us on the map.]