although the basic concept for the film was fonda's, the title "easy rider" was provided by southern (it is slang term from the american south for a prostitute's lover who lives off her) and southern wrote several early drafts of the screenplay. during the production, southern became concerned at hopper and fonda's replacement of his writing by what he described as "dumb-bell dialogue", and more of the material southern wrote for the main characters was cut out during the editing process. also fonda and hopper mostly improvised a great deal as they filmed.