The phrase comes from Inception, Christopher Nolan's 2010 film about thieves who enter shared dreams, where going deeper means entering a dream inside another dream. As the film's layered structure became part of popular culture, the line was lifted into edits, reaction videos and memes about anything with hidden levels, from nested jokes to endless comment threads. It endures because the idea is instantly understandable even without seeing the film: deeper is never simpler, it is stranger, riskier and harder to leave behind.