Then all I can say is that your ideas of humour are peculiar, my dear Rita. Mrs. Vandemeyer smiled.
Mrs. Vandemeyer's sense of humor was rather tame, so she was taken aback by Rita's humor. 
mnli hypothesis: Mrs. Vandemeyer's sense of humor was rather tame, so she was taken aback by Rita's humor.  premise: Then all I can say is that your ideas of humour are peculiar, my dear Rita. Mrs. Vandemeyer smiled.