Okla. Stat. tit. 21, § 1365

Any person, other than a railway employee in the discharge of his duty, who, without authority from the conductor of the train, rides, or attempts to ride, on top of any car, coach, engine or tender, on any railroad in this state, or on the drawheads between the cars, or under cars or trussrods or trucks, or in any freight car, or on the platform of any baggage car, express car, or mail car, or any train in this state, shall be guilty of a misdemeanor.