<?php

class Pituh {
	public $kurochka = 'Ko-ko-ko';
    public function kurarek() {
    	global $kudah;
        echo $$this;
    }
    public function __toString() {
        return 'kudah';
    }
}

$koko = new Pituh();

$kudah = 'Сам дурак';

$koko->kurarek();