Could you explain this Hamlet quote?

This quote takes place in Act 3 as the actors are putting on a play chosen by Hamlet for the king, Claudius, and the queen who is Hamlet's mother. The play is staged somewhat similar to the death of Hamlet's father in which a king is sleeping on stage and a man walks on and pour poison into the king's ear. As this scene is happening, Ophelia asks Hamlet what's going on and Hamlet comments "This is miching mallecho, it means mischief." In the scene there's mischief going on, and Hamlet is in a way being mischevious. In a sense he's giving away part of his plan to Ophelia (but she really has no idea) which was to get the reaction from his uncle, Claudius. Hamlet wanted to be sure it was Claudius who killed his father.

I think the answer is nobody knows. This link is to the beginning of an article about "miching malleco" in the Journal of English Studies. I can't get to the full article from here, but maybe you could get to it from your local library, or from a high-school or college library. http://links.jstor.org/sici?sici=0034-6551(196702)2%3A18%3A69%3C40%3AHII1%3E2.0.CO%3B2-I

I love Shakespeare but am not too familiar with Hamelt, surprisingly. I could tell you that it probably means that something or someone is causing trouble.