Telford Taylor's "The Anatomy of the Nuremberg Trials: A Personal Memoir" describes a scene that might be this.

tldr; Goering had a huge ego and was a famous "medal collector." A presenter misspoke on Hitler's line of succession and Goering corrected him by waving his arms shouting "I was the second!" The outburst of vanity made everyone laugh.

"On the third day of the trial I witnessed, by chance, an episode which, apparently, no one else noticed and which gave me an impression of Hess's condition. I was sitting in the courtroom at the American Prosecution table while Ralph Albrecht was delivering his lecture on German governmental structure. It was my first opportunity to scrutinize the defendants and their counsel at leisure and close range. I was not paying close attention to Albrecht's presentation, but I heard him say that Hitler's "successor-designate was first the Defendant Hess and subsequently the Defendant Goering." This I well knew to be in error. The names were right but the order was wrong; Goering was number two and Hess number three.

Since I was sitting barely twenty feet from those two gentlemen, I looked to see whether either of them had noticed the slip and, if so, how he reacted. Goering was already waving his arms to attract attention, pointing to himself, and saying repeatedly: "Ich war der Zweite!" ("I was the second!") As these protests were pouring out of Goering, Hess turned and looked at him and burst into laughter. It appeared to me that Hess also knew that Albrecht had misspoken (Albrecht corrected the order of succession at the end of his presentation), and was vastly amused by Goering's characteristically vain reaction. I inferred from this occurrence that Hess's amnesia was not as complete as he had given out."

Telford Taylor's "The Anatomy of the Nuremberg Trials: A Personal Memoir" describes a scene that might be this.

"On the third day of the trial I witnessed, by chance, an episode which, apparently, no one else noticed and which gave me an impression of Hess's condition. I was sitting in the courtroom at the American Prosecution table while Ralph Albrecht was delivering his lecture on German governmental structure. It was my first opportunity to scrutinize the defendants and their counsel at leisure and close range. I was not paying close attention to Albrecht's presentation, but I heard him say that Hitler's "successor-designate was first the Defendant Hess and subsequently the Defendant Goering." This I well knew to be in error. The names were right but the order was wrong; Goering was number two and Hess number three.

Since I was sitting barely twenty feet from those two gentlemen, I looked to see whether either of them had noticed the slip and, if so, how he reacted. Goering was already waving his arms to attract attention, pointing to himself, and saying repeatedly: "Ich war der Zweite!" ("I was the second!") As these protests were pouring out of Goering, Hess turned and looked at him and burst into laughter. It appeared to me that Hess also knew that Albrecht had misspoken (Albrecht corrected the order of succession at the end of his presentation), and was vastly amused by Goering's characteristically vain reaction. I inferred from this occurrence that Hess's amnesia was not as complete as he had given out."