Marullus seems to sense that by entering into this civil disorder he is committing a crime. This fear foreshadows what happens. In Act 1, Scene ii, Casca tells Cassius and Brutus that the tribunes Marullus and Flavius, Caesar's political enemies, have been caught disrobing the statues. They have been put to silence.
He tricked his friends into thinking white-washing was fun. His friends, wanting to experience white-washing, traded him things in exchange for being able to white-wash the fence for a while.