Unlike Hedy Lamarr, who actually patented a “secret communication system” during WWII (though the idea wasn't ultimately tweaked and used until the 1906s), Jayne Mansfield didn’t create this product - she just inspired it.
Mansfield was one of the most visible starlets of the 1950s and ‘60s and was constantly compared to Marilyn Monroe for both her platinum blonde hair and her physical, um, assets.
On June 29, 1967, Mansfield, her lawyer, her driver and three of her five children were driving from an appearance in Biloxi, Mississippi, to New Orleans for a TV interview early in the morning. It was just before 2:30 a.m. when her car came up on a tractor-trailer too fast, not seeing it because of anti-mosquito fog clouding the highway. The small car didn’t just rear-end the tractor-trailer; it went completely underneath it, shearing the top of the car off. It also killed the three adult passengers of the car almost instantly. Pictures of the accident site were pretty gruesome; a mass of blonde hair sitting all by itself made people wonder if Jayne had been decapitated or had simply lost her wig. Snopes reports that Mansfield was not decapitated, but she probably was scalped, or something close to it.
Shortly thereafter, the National Highway Traffic Safety Administration made it mandatory for all semi truck trailers to be fitted with under-ride bars, also called DOT bars or Mansfield bars. The steel bar hangs from the main cab and is designed to stop a car before it rolls underneath the trailer (it's the red striped bar hanging down from the semi pictured).
Amazingly, the three children in the backseat survived with minor injuries. One of them went on to follow in her mother’s actress footsteps - you might know her as Law & Order’s Detective Olivia Benson, AKA Mariska Hargitay. She still has a scar from the crash that happened when she was just three years old.