It's a private browsing mode through Google Chrome, so it doesn't store your history or cookies once you close the browser. I had read that cookies are typically what cause the problems on the passholder section on Disney's site, so using the incognito tab prevents Stitch from appearing! You can just delete cookies from your usual browser, and this will usually work for a little while, but (at least in my experience) the cookies have to be repeatedly deleted every so often.