Get random value from JSON using ONLY parse and Math.random WITHOUT loops, arrays and Object.keys

I have got a JSON:

let jsonName  = '{"name1": "John", "name2": "Billy", "name3": "Tristan"}';
let jsonSurname  = '{ "surname1": "Doe", "surname2": "Smith", "surname3": "Dodson"}';

I need to get random value from both jsonName, jsonSurname (for example "John" and "Doe") and parse this two values into one object. I must to use Math.random. There can't be loops, arrays, Object.keys, Object.entries, Object.values, Object.getOwnPropertyNames.

I think that i must to use parse somehow for both properties:

JSON.parse(jsonName, function (key, value) { 

 // SOME MAGIC with Math.random

  });

Help me please!