When Sheldon and Leonard go over to Penny's apartment to drop off a box of flat pack furniture that came for her, Sheldon is deeply disturbed when he sees how messy and disorganized her apartment appears. Later that night, while Penny sleeps, Sheldon sneaks into her apartment to clean and organize it; Leonard catches him and reluctantly helps him clean.
The next morning, Penny realizes that they had been in her apartment and becomes furious. Sheldon tries apologizing to Penny but fails after remarking that Leonard is a "gentle and thorough lover". Later, Penny encounters Raj in the hallway and talks to him, finally reasoning with herself that the guys were just trying to help her though Raj doesn't utter a word as he is not able to speak to women, unless drunk, due to his selective mutism. Leonard then apologizes, prompting Penny to hug him and forgive him.Title reference: Sheldon having Big Bran cereal (with higher fiber content) after Penny finds out her apartment has been rearranged.