The simplest example of DynamicObject I could come up with...

gistfile1.cs

using System;
using System.Collections.Generic;
using System.Dynamic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Newtonsoft.Json;

namespace AWordAboutDynamic
{
    class Program
    {
        public class PersonData : DynamicObject
        {
            private Dictionary<string, object> _store = new Dictionary<string, object>();

            public override bool TryGetMember( GetMemberBinder binder, out object result )
            {
                if( _store.ContainsKey( binder.Name ) )
                {
                    result = _store[ binder.Name ];
                    return true;
                }
                return base.TryGetMember( binder, out result );
            }

            public override bool TrySetMember( SetMemberBinder binder, object value )
            {
                if( _store.ContainsKey( binder.Name ) )
                {
                    _store[ binder.Name ] = value;
                }
                else
                {
                    _store.Add( binder.Name, value );
                }

                return true;
            }

            public string ToJson()
            {
                var builder = new StringBuilder();
                using( var writer = new StringWriter( builder ) )
                    new JsonSerializer().Serialize( writer, _store );
                return builder.ToString();
            }
        }

        static void Main( string[] args )
        {
            // create a new persondata
            dynamic personData = new PersonData(); // show how this won't work if you use "var"

            // set a value into our persondata
            personData.name = "Jared Barboza";
            personData.address = new
            {
                address1 = "10 main st",
                address2 = "apt 12",
                city = "Boston",
                state = "Massachusetts",
                zipcode = "01754"
            };

            Console.WriteLine( personData.ToJson() );

            Console.ReadLine();
        }
    }
}

oops, forgot to say that this requires Json.net...