Also known as the "Grandfather Paradox of Time Traveling Hipsters," this phenomenon occurs when a time traveler attempts to create a paradox by going back in time and preventing their own existence from occurring. However, this paradox is only possible if the time traveler is aware of the paradox and has the ability to prevent it, creating a bootstrap paradox.
This paradox is often used in science fiction as a plot device, but in reality, it's just a fancy way of saying "I went back in time and now I'm confused."
Learn more about the Grandfather Paradox
Or, if you're feeling particularly philosophical, check out the Predestination Paradox