That would be irony! (Situational irony, if you wish to be more specific.)
something you didnt expect to happen
Rarity is when something is very rare and can only happen when you least expect it...rare-ity. It also happens to be the name of one of the pony characters in "My little pony: friendship is magic".
I believe they called it South Park because there is 17 cities in USA that's called South Park. The reason to do that is because what happens in South Park could happen in any town.
In movies they've used scarabs, and don't expect it to happen outside a movie.
Your Face happen
Irony is when the opposite of what you would expect to happen actually happens. A firehouse burning down to the ground is ironic because you would never expect that to happen.
When something happens that is the exact opposite of what you expected to happen, this is called irony. An example would be getting candles to relieve your stress and them accidentally burning the house down.
When something happens that you don't expect, it is often referred to as a surprise or an unexpected event. This can also be characterized as an anomaly or an unforeseen occurrence. Such events can evoke various emotions, ranging from excitement to confusion, depending on the context.
It is called dramatic irony. Dang you beat me to it. And situational irony is when something unexpected or opposite of what you thought was going to happen happens.
That is called 'unexpected'.
That incident could be described as a surprise; or as a reality check.
In the scientific method this would be called the "hypothesis".
the opposite of "happen" is "dematerialize"
That concept is known as irony. It involves a discrepancy between expectation and reality, often manifesting in a situation that is the opposite of what one would expect.
there is a contrast between what is expected to happen and what actually happens. This can be in situations, events, or statements where the outcome is the opposite of what is expected or intended. Irony often involves humor or sarcasm.
A statement that describes what scientists expect to happen every time under a particular set of conditions? Answer: Scientific Law
that probibly will never happen because we are to deep into the mess of global warming to expect much change for the better.