Schema::create('friend_user', function(Blueprint $table) {
    $table->increments('id');
    $table->integer('user_id')->unsigned();
    $table->integer('friend_id')->unsigned();
    $table->timestamps();
});

$friend_user = array(
        array(
            'id' => 1,
            'user_id' => 1,
            'friend_id' => 3,
        ),
        array(
            'id' => 2,
            'user_id' => 4,
            'friend_id' => 1,
        ),

    );

public function friends()
{
 return $this->belongsToMany('User', 'friend_user', 'user_id', 'friend_id');
}

foreach(Auth::user()->friends as $i) {
    var_dump($i->id);
}

public function friends()
{
  return $this->belongsToMany('User', 'friend_user', 'user_id', 'friend_id');
}

// Same table, self referencing, but change the key order
public function theFriends()
{
  return $this->belongsToMany('User', 'friend_user', 'friend_id', 'user_id');
}

//You can then call opposite record(s) using:
foreach( Auth::user()->theFriends as $theFriends )

public function friends()
{
 return $this->belongsToMany('User', 'friend_user', 'user_id', 'friend_id')->orWhere('friend_id', $this->id);;
}