using System;

public class Program

{

    public static void Main()

    {

        Meme meme = new Meme();

        Joke joke = new Joke();

        joke.Content = "Some Joke";

        Joke anotherJoke = new Joke();

        anotherJoke.Content = "Another Joke";

        meme.setJoke(joke);

        Console.WriteLine("This is first joke {0}", meme.joke); 

        meme.joke = anotherJoke; // mutate

        Console.WriteLine("This is second joke: {0}", meme.joke);   

    }

}

​

public class Meme 

{

    public Joke joke;

    public void setJoke(Joke newJoke)

    {

        this.joke = newJoke;

    }

}

​

public class Joke 

{

    public string Content { private get; set; }

    public override string ToString()

    {

        return Content;

    }

}