Catsup (ketchup!) + mayo + pickles.
A neighbor who liked to think of herself as racy used Heinz cocktail sauce instead of ketchup for her Thousand Island. Living on the edge!
The only way!
For some reason there was also one lone bottle of French dressing in our refrigerator for I swear like seven years which nobody ever touched. I think it finally got thrown out when we replaced the fridge.