Cuoco appeared backstage during the blind auditions of the September 30 , 2013 episode of the vocal talent reality television show '' The Voice '' , offering moral support to her younger sister , Briana , who made it through the auditions and chose Christina Aguilera as her mentor .
Cuoco appeared backstage during the blind auditions of the season 5 of the vocal talent reality television show '' The Voice '' , offering moral support to her younger sister , Briana Cuoco , on an episode broadcast on September 30 , 2013 . 
 Briana made it through the auditions and chose Christina Aguilera as her mentor .