Something Old, Something Blue - S6-E18
Corrected entry: In the scene where Jill went to talk with Irene who was really worried and almost crying in the bride's room Jill made a joke. When the camera showed the mirror behind Jill, you could see that Irene was madly laughing. When the camera showed Irene again, she was almost crying. (00:18:00)
Correction: The description embellishes what is going on. Ilene is anxious and doubtful, but she isn't almost crying. Also, Ilene made the joke, not Jill, which was a remark about Ilene being bothered by Al's snort that she hints he does while making love too. This TMI remark causes a funny, disgusted reaction from Jill, and Ilene can be seen smiling. But this isn't a mistake because a smile is a natural response after making someone laugh with a joke.