How about the following version:
Everything that can go wrong, will go wrong, except when it doesn't.
What's the point of it then?
So I can write a set of meshugener's laws:
Everything that can go right, will go right, except when it doesn't.
Everything that can be sad, will be sad, except when it doesn't.
Everything that be a jerk, will be a jerk, except when it doesn't.