A condiment fit for kings, consisting of equal parts tomato ketchup and mayonnaise. Differs from fry sauce in that the two sauces are not mixed fully but rather placed next to each other, whereby the fries are dabbed from one sauce into the next and they mix naturally. French fries are the primary recipient of tomayo, but other dippable consumables can also be used, e.g. the chicken nugget.
Friend 1: "Hey man, I've got some fries. Want me to get some ketchup?"
Friend 2: "If it ain't tomayo I'm not touching those fries."