http://www.geeksugar.com/Star-Wars-Comic-Con-18387597
1976 Comic Con
http://www.myremoteradio.com/blog/movies/1976-comic-con-fans-see-star-wars-for-the-first-time
According to cartoonist Phil Foglio, they were selling shares in "The Star Wars Corporation" at the con. Foglio has regretted not buying some shares ever since!