A "fizz" is a mixed drink variation on the older sours family of cocktail. The latest addition is the Smirnoff Sours vodkas, introduced in 2014. During fermentation, the cream naturally sours as bacteria convert milk sugars into lactic acid. The egg white sometimes employed in other whiskey sours is not usually included. Common examples of sours are the margarita and the sidecar. As the series progresses, their friendship sours. The pregnancy sours the friendship between Wilfred and Shannon's father, Harlan, a neighboring farmer. Their relationship sours quickly because Swan is angered by Chamalis's destructive power-mongering. Consequently, their relationship sours and eventually ends. Eventually, however, the relationship sours. Gary gets involved with the Dixie Mafia, specifically Wynn Duffy, and their marriage sours. Eventually Joel manages to influence Bart again and it sours the relationship. The process of acidogenesis is similar to the way milk sours. Their relationship sours, as the narrator intermittently fights with Sonny. Although Holden's date initially goes well, it soon sours after Sally introduces her friend George.