NEW YORK—Jake Hellmann, 19, whose rowdy nightclub exploits have made him a tabloid staple, has behaved in a manner unbefitting his stature as heir to the Hellmann's mayonnaise throne, family sources reported Tuesday. "When one is fortunate enough to the carry the name of America's most popular mayonnaise, one does not spend every night getting drunk and partying with models," said his great uncle Oliver Hellmann, 79. "Clearly, young Jake is not yet ready to accept the enormous responsibility that comes with being a mayo magnate."