Baboon is right. Mayo can add a lot to some foods. And I'll be honest, it took me some time to embrace using mayo other than on a sandwich too.
Exactly, mayo is used in actual cooking in addition as a condiment. The main ingredients of mayo are eggs and oil. I make a John Wayne Casserole (biscuit bottom crust, taco meat, onions, peppers, tomatoes, cheese topcrust) and mayo is a major component of the topcrust.