Premise: For Those Who Think Young is a 1964 beach party film shot in Techniscope, directed by Leslie H. Martinson and featuring James Darren, Pamela Tiffin, Paul Lynde, Tina Louise, Bob Denver, Nancy Sinatra, Robert Middleton, Ellen Burstyn (billed as Ellen McRae), Claudia Martin and Woody Woodbury.
Hypothesis: Nancy Sinatra was in a beach movie in 1964.