Yes mayonnaise can be put on a hot dog if you want the mayonnaise on the hot dog.
I tried mayonnaise on a hot dog after my brother started putting mayonnaise on his hot dogs when we were kids and I started liking it.
I like both mayonnaise and Ketchup as well as radish on the hot dog which makes a great combination and makes the hot dog taste much better to me.
Some people may not like mayonnaise on their hot dog but you can try it and if you don't like it then you'll not want to put anymore on your next hot dog.
But try the mayonnaise on your hot dog and I'm sure you'll like it.
I like to even make mayonnaise sandwiches with hot dog buns or even just plain sliced bread.