Klein, 77, visited the Forth Worth Museum of Science and History as part of the "Elvis at 21" touring history exhibit.
The event also features Alfred Wertheimer's oversized, candid photos of the singer, the Fort Worth Star-Telegram reported.
Klein met Elvis in eighth grade and was friends with him until his 1977 death. Much of his talk focused on Elvis' way with the ladies.
"Every girl I ever called to see if she would meet Elvis, none of them ever refused," he said.
He also talked about being mobbed by Elvis fans once in Canada, the Star-Telegram said.
"They broke the aerial [antenna], they took the license plate -- this guy ran his knife down the side just to get paint scrapings from Elvis' car. We barely got out of there," he said.