Todd and the Book of Pure Evil (2010)

S1E8 Cockfight

Todd and Curtis pull a prank on a bully with a small endowment, but their scheme takes an unexpected turn. The bully taps into The Book's mysterious powers, transforming his diminutive appendage into a fearsome cockmonster. As chaos ensues, Todd and Curtis must confront the consequences of their actions and find a way to reverse the transformation before things spiral further out of control.