Ketchup enhances most things.....

Mayo on fries is like warm potato salad. German in origin and adopted across Europe particularly in Belgium where potato fries were first created.

It is also a very popular way for people in the Southern US to eat fries.

I prefer fries with mayo over any other condiment.

I always say, don’t knock it unless you have tried it.

A lot of opinions here seem to be judge first before trying. I like to do the opposite, try first and then decide if I like it...and don’t judge others that have a different opinion AFTER they have tried it.
mayo on fries is good. vinegar OK. Milkshakes and fries go good together, so dip em in if you like.lol
I like to try new foods. But putting tomatoes in my cake and ice cream just doesn't appeal to me. Is it horrible? Perhaps not. And while it may be palatable, just seams so unnecessary. Most likely making it less enjoyable for me. I'd probably take a taste. 'Yep, that's good'... and grab something else.