The "GOUT" is what fans affectionately call the 2006 Bonus DVDs of the original Star Wars Trilogy. It is short for 'George's Original Unaltered Trilogy'.
Why would you want to "GOUT Sync" a version of Star Wars?
Over the years, fans have created many fan edits of the original Star Wars films - some are already based on the 2006 Bonus DVDs, but many others are from VHS tapes, laserdiscs, Super 8 films, 16mm films, 35mm films, and the official Blu-rays. By matching each source, frame to frame with the American NTSC GOUT Bonus DVDs, fans can take advantage of the many official and fan created audio mixes, commentary, language and subtitle tracks. It also means that if there is a problem with the transfer, all you have to do is point to the GOUT frame number and everyone can be sure that they are talking about the same frame.
More info: http://www.thestarwarstrilogy.com/starwars/post/2017/03/07/How-to-GOUT-Sync-Star-Wars