[Biesmen]

Or, more efficient:

pawn Code:

public OnPlayerSpawn(playerid)
{
   TogglePlayerControllable(playerid, false);
   ShowPlayerDialog(playerid, 1, DIALOG_STYLE_LIST, "Rules here", "Understood", "Cancel");
   return 1;
}

public OnDialogResponse(playerid, dialogid, response, listitem, inputtext[])
{
   if(dialogid == 1)
   {
      if(!response) // If he clicked on "Cancel"
      {
         Kick(playerid); // It will kick him
         return 1;
      } else {
         TogglePlayerControllable(playerid, true);
      }
      return 1;
   }
   return 0;
}