Wham, Bam, Thank You, Mammy - S6-E5
Corrected entry: Blanche's nanny remembers seeing Blanche in a white dress at her wedding. But in a different episode, Blanche celebrates her anniversary by trying on her RED wedding dress. She explains that even she couldn't keep a straight face in a white dress.
Correction: Mammy's exact words are "Did you or did you not wear your first formal white dress with pink flowers to your junior prom". She was not talking about Blanche's wedding.
mrsjaybubba