To provide an answer, context is crucial as “this” could refer to any number of situations, objects, or phenomena. Generally speaking, if “this” refers to an unexpected event or occurrence, it could have been a natural event, a misunderstanding, a technological error, or a myriad of other possibilities depending on the specifics of the situation in question. Without more concrete details, it’s challenging to narrow down the answer. For instance, if it involves a sudden occurrence in a natural setting, it might have been a rare weather phenomenon or an uncommon wildlife sighting. If related to technology or machinery, it could be a software glitch or hardware malfunction. Understanding the context and surrounding conditions would greatly aid in accurately identifying what “this” might have been.