Shaquille O'Neal did an interview with Extra and talked about the NBA bubble. Shaq said that the lack of fans could be an advantage for some, but noted that he once played his best game because he saw Halle Berry in the crowd. Let's check that fact.
Shaq says that the game was "at the Knicks." According to Basketball-Reference, Shaq only had two games where he scored more than 40 at Madison Square Garden in his career. In 1994 he had 41 points and 17 rebounds in a Magic loss to the Knicks. Then in March 2000 he had 43 and 10 in a Lakers win.
Unfortunately for this story, neither of those games would qualify as his "best game." Shaq had two other games against the Knicks where he put up 40+ in Orlando and one in Los Angeles. The one in LA would make more sense for Berry to be in attendance, but Getty has no images to corroborate that story.
Considering Shaq once had 61 and 23 in a game, I don't know if any of those contests would count as his best. It would actually make sense if Halle Berry was at that game on March 6, 2000 when Shaq had the highest-scoring game of his career against the Clippers. It was awards season and Berry lives in California. On January 23, 2000 she won a Golden Globe for her role in "Introducing Dorothy Dandridge." Then on March 12, 2000 she won a NAACP award in Pasadena.
So it is possible that Halle Berry saw Shaq play well against the Knicks at Madison Square Garden, but he did not play his best game that night. It's also possible Halle Berry did see Shaq play his best game, but only Halle Berry knows for sure.
Berry and O'Neal would appear together on the Nickelodeon Kids Choice Awards in 2001. Shaq had 24 points and 20 rebounds the next night as the Lakers started a legendary postseason where they went 15-1 on the way to their second straight title. Coincidence?