Ginny (no last name is ever given) is the old high school girlfriend of Jack Koster. She works as a waitress, though Theresa (for some reason) assumes she could be a cashier in Jack's father's store.[1]
Ginny shows up one Friday night when Jack and some of his friends are having a party. Ginny is portrayed as not being aware of Jack's relationship with Theresa, and gets uncomfortable when the latter walks in on them together.[2] Theresa goes up to her room to change into a sexy outfit to make Jack jealous, but meets Steve instead. Steve and Theresa head downstairs, where she assures Ginny that their relationship meant nothing.[3]
Even though Theresa says she "felt sorry for Ginny"[4] regarding the confrontation between her and Jack, Theresa also often looks down on Ginny's social class. She describes Ginny as "the poor waitress...waiting on tables all [her] life," sitting at home "hoping [she] could keep a college educated man."[5] Later on, when Theresa becomes rich and famous, she thinks to herself, "Theresa calling Jack. How are you doing with Ginny?"[6] Theresa's treatment of Ginny, in fact, is one of the reasons readers opine Theresa is an unlikable character.