An ostomy coupling is disclosed comprising a floatable coupling part. The coupling part is supported with respect to an adhesive wafer by means of a flexible support collar that permits displacement of the coupling part in a floatable manner. The flexible collar comprises plastics film and has bistable shapes. The collar is configured to hold the coupling part stably in (i) an extended position spaced from the adhesive wafer, to facilitate an ostomate to manually brace the coupling part in order to relieve the attachment force when an ostomy appliance is press fitted to the coupling part, and (ii) in a retracted position close to the adhesive wafer.