Cantillon Crémant de Gueuze
Description
It has been confirmed by Jean and Jean-Pierre Van Roy that this beer doesn't exist, despite being referenced to by a few links you can find below.
References
Belgian Collector's List - http://www.jacquestrifin.be/brasseries_bieres/bruxelles_cantillon.php
Belgian Label Service - http://users.telenet.be/label.service/brew.htm
A brief description - http://www.bierebel.com/forum/viewtopic.php?f=1&t=2859