Fortified fuel?
I was told by a former sergeant of how the RAF out in Cyprus used to keep back pairs of drop fuel tanks from use. Periodically when a Tornado was flying back to Blighty they would all club together and fill one of these pristine tanks with brandy and the other with sherry IIRC, thereby sidestepping customs duty charges on quite a large scale. Of course, this endeavour wasn't without its risks; on one occasion the pilot hit a patch of turbulence over Germany and immediately jettisoned the tanks, much to the disappointment of all concerned. Anonymous to protect the innocent from the guilty.