The Horrible Secret!! (恐るべき秘密!!, Osorubeki Himitsu!!) is chapter 335 of the Naruto manga.
Team 10 realises that they cannot compete with Kakuzu's extra hearts and Hidan's immortality at the same time. Shikamaru volunteers to break Hidan away from Kakuzu to allow the others to fight Kakuzu alone. After Kakashi hands something to Shikamaru, Shikamaru tries to catch Hidan with his shadow. Having been caught by his shadow several times now, Hidan does his best to avoid it. In doing so, he does not notice Shikamaru getting close to him. Shikamaru punches him, joining their shadows and letting him trap Hidan.