Early Kirsten Flagstad's huge B5s and interpolated high C as Kundry

'Early' used liberally here as she was already 43 here, but this is the earliest recording you will find of Kirsten Flagstad as Kundry (Parsifal, 1938 @ the Met).
Flagstad was in exceptionally good form on this day, her family (sister and mother) were visiting from Norway so she must have wanted to make the performance extra special. This scene was complete with a huge interpolated high C on the "HaHa!". I do believe this was intentional, and not a sharp B, as she also did the same thing later at Covent Garden ( • Kirsten Flagstad's mon... ).
Parsifal - Lauritz Melchior
Conductor - Erich Leinsdorf