The trend is largely driven by viral "life hack" videos. These videos suggest that appending the code to your search query forces Google to index specific directories or file servers that contain the full movie or APK file.
If a movie isn't available on these, wait for a sale, rent for $3–$5, or use your local library's DVD collection. Your device's security and the future of cinema are worth more than a shady download.
: The term originated from a leaked Microsoft Office 2000 product key (specifically XXXXX-XXXXX-XXXXX-XXXXX-94FBR Search Psychology