The blonde actress had to don the large prosthetic lobes for her role as a checkout girl in the comedy 'Employee of the Month'.
A film source said: "Jessica had to wear them all the time even when you couldn't see them." Jessica - who stars alongside comics Dax Shepard and Dane Cook - plays Amy, a hot new shop girl who only dates employees of the month.
Rumours have been rife that Jessica and Dane have been dating.
It has even been claimed that Dane asked Jessica - the ex-wife of Nick Lachey - to join him for an autumn holiday.
The pair host the Teen Choice Awards together on August 20.