Which ingredient is NOT included in a Dirty Martini?

A Dirty Martini typically includes vodka or gin, dry vermouth, and olive juice. The addition of olive juice is what characterizes it as "dirty," giving the drink a savory flavor.

Triple sec, on the other hand, is a citrus-flavored liqueur and is not used in the preparation of a Dirty Martini. It is commonly found in cocktails like Margaritas or Cosmopolitans, where a sweet and citrusy flavor profile is desired. Therefore, the choice of Triple sec is appropriate for this question, as it does not fit within the standard ingredients of a Dirty Martini.