Complex sentence: When Radar O'Reilly, who's in on the fact Tuttle doesn't actually exist, explains to Henry Blake how Tuttle already signed the supply form, Blake realizes Tuttle has never pulled any O.D. duty and makes him Officer of the Day.
Split into simpler sentences: When Radar O'Reilly, who's in on the fact Tuttle doesn't actually exist, explains to Henry Blake how Tuttle already signed the supply form. Blake, realizing Tuttle has never pulled any O.D. duty, makes him Officer of the Day.