Since I came to Vegas I have been working more and more in the world of stand-up comedy. It's a good time had by all and many of the traits of comedy are shared and/or mirrored in the magic world.
Take for instance theft. Jokes are lifted willy-nilly (or maybe it's willy-nelson?) without giving proper credit or any remorse for the crime. It's very similar to what some in the magic fraternity deal with... except a line is much easier to steal than a trick because jokes are take no money or practice to use. (Which isn't entirely true, but try telling THAT to a hack)
That however is not the focus of this post. Not by a long john silver shot. This is about the end... of your routine that is. All too often I have heard an audience member know the end of a joke before the joke slinger tells it. Why is this? Perhaps they have heard it before? Nay! It' because the punchline is too predictable.
The same goes for any magic act. If the audience gets to the conclusion of an effect before you do, the jig is up.. and gone! This means your material is trite, predictable, and easily forgettable. What's even worse is if they ste up a BETTER ending in their mind than what you actually do. At that point they are more clever and amazing than you.
There is an upside to this line of thought however.
You can use this idea to turn the tables on those smarmy bastards. Take something that is INTENTIONALLY predictable and turn it on it's side (and thereby putting them on their asses). Take what they and/or assume and use it against them! If they think something is going to vanish, make it transform. If it's supposed to appear, make it something they don't expect. Many magicians have used this to their advantage. It works especially well with other magi who KNOW the tricks. (If you have ever seen Fantasio perform his Funtasio routine, you know what I mean))
If your magic is 2+2=4 then change up the equation so they never see it coming.
I prefer 2+2=fish myself.