Based on how I've observed certain condiments being used on various food items. Ketchup Dos: French Fries Hash Browns Hamburgers Ketchup Dont's: Eggs Chili Hotdogs Pizza Mustard Dos: Corndogs French Fries Hamburgers Hotdogs Sandwiches Mustard Don'ts: I can't think of any Mayonaise Dos: Hamburgers Sandwiches Mayonaise Don'ts: Hotdogs comments........... People putting ketchup on a hotdog or corndog makes me want to barf. When someone loads up a bowl of chili with ketchup, I want to barf. Ranch dressing is not really a condiment, but I sometimes like to dip my fries or potato chips in it. It is also really good on a hamburger. I also use it with pizza sometimes. Ketchup is probably the most widely used condiment IMO. When I was in China, I observed people using ketchup with pizza in the sameway some people use ranch dressing with pizza. There was a ketchup bottle on every table. It is a bad combination in my opinion.