namespace hphack
{
  using System;
  using System.Text;
  using System.Net;
  using System.Net.Sockets;

  public class PrnHack
  {
    public static int Main(string[] args)
    {
      if(!ParseArgs(args))
      {
        return -1;
      }
            
      Console.WriteLine("\nHP Display Hack");
      Console.WriteLine("Host: {0}", args[0]);
      Console.WriteLine("Message: {0}\n", message);
            
      IPEndPoint ipEndPoint;
      ipEndPoint = new IPEndPoint( Dns.Resolve(args[0]).AddressList[0], PJL_PORT);

      Console.WriteLine("Host is {0}", ipEndPoint.ToString());

      Socket socket;
      socket = new Socket(
                        AddressFamily.InterNetwork,  
                        SocketType.Stream, 
                        ProtocolType.Tcp
                     );

      socket.Connect(ipEndPoint);

      byte [] sendData;
      string sendString;

      sendString = String.Format(
                "\x1B%-12345X@PJL RDYMSG DISPLAY = \"{0}\"
\x1B%-12345X
", 
                message
           );

      sendData = Encoding.ASCII.GetBytes(sendString);
                
      int result;
      result = socket.Send(sendData, sendData.Length, 0);

      if(result == 0)
      {
        Console.WriteLine("Could not send on socket");
      }
        
      socket.Close();
        
      Console.WriteLine("Finished\n\n");
      return 0;
    }

 

    protected static bool ParseArgs(string[] args)
    {
      if(args.Length != 2)
      {
        Console.WriteLine(
                  "HP Display Hack: " + 
                  "hphack printername \"message\" "
            );
        return false;
      }

      if(args[1].Length > 16)
      {
        Console.WriteLine("Message must be <= 16 characters");
        return false;
      }
        
      if(args[1].CompareTo("random") == 0)
      {
        message = GetRandomMessage();
      }
      else
      {
        message = args[1];
      }

      return true;
    }


    public static string GetRandomMessage()
    {
      string [] Messages = { 
                             "BUZZ OFF", 
                             "TOUCH ME",
                             "STEP AWAY",
                             "SET TO STUN",
                             "SCORE = 3413",
                             "PAT EATS MICE",
                             "FEED ME",
                             "GO AWAY",
                             "NEED MORE SPACE",
                             "POUR ME A DRINK",
                             "IN DISTRESS",
                             "NICE SHIRT",
                             "GO AWAY",
                             "NO PRINT FOR YOU",
                             "RADIATION LEAK",
                             "HANDS UP",
                             "PRESS MY BUTTON",
                             "TAKE ME HOME",
                             "LOOKS LIKE RAIN",
                             "HELLO WORLD",
                             "NICE HAIR",
                             "NEED A MINT?",
                             "BE GENTLE",
                             "BE KIND",
                             "INSERT DISK",
                             "BUY ME LUNCH",
                             "DONT STOP",
                             "COME CLOSER",
                             "TAKE A BREAK",
                             "INSERT QUARTER",
                             "BLACK SABBATH"
      };


      Random r = new Random();
      return Messages[r.Next() % Messages.Length];
    }

    protected const int PJL_PORT = 9100;
    protected static string message = "NO MESSAGE";
        
  }
}

http://www.odetocode.com/Humor/68.aspx

I have not tested it yet but the author claims to make your printer show some random messages.

Fun with C# and HP Laserjet

c

C#