Some people love going for the unofficial fries and shake dip combo, so this isn't that weird.
I would imagine they just don't salt the fries or salt them way less and have a sweet with a slightly salty chocolate sauce.
As far as wacky food goes, this is not even a little weird. My family is from all over the world and i find it odd how squirmish some people get with fairly normal foods. For example, when i went to university, there were 11 other people in my dorm building. Only one of them would touch liver/kidney despite others never given it a go. Three of the girls wouldn't eat meat if it was connected to a bone despite knowing full well that chicken breasts and boneless thighs were at some point attached to the rest of the chicken. I told them about a dish from the Phillipines we call blood pudding and it is pretty much like a stewed (rather than boiled and shallow fried), meatier version of black pudding, they had to stop me before they were going to be sick.
They would quite happily chug a litre of red bull, drink VKs all night and eat spaghetti and ketchup for dinner.
Well, each to ones own.
