Act III, Scene III: How much do the watchmen understand of what they have found?

One of the night watchmen, having overheard this story, arrests Borachio and Conrad for villainy. They agree to go peacefully and are taken to be judicially interrogated. I don't think they really understand the specific nature of their villainy, the watchmen are comic characters, but they are eager to be recognized for catching somebody with ill intentions.