Custard down your vest
"When moved slowly, the molecules will slip past each other, but in a high-energy impact they will snag and lock together, becoming solid," said Richard Palmer, who invented the gel. "In doing so they absorb energy."..The substance relies on "intelligent molecules" that "shock lock" together to absorb energy and create a solid pad. Once the pressure has gone they return to their normal flexible state.
"intelligent molecules my arse - they are just stuffing the vests with custard. Non-Newtonian fluids have given me and my loved ones hours of fun but don't over-egg the discovery.
(My secret plan for untold wealth is to patent sleeping policemen filled with such a gel, drive over slowly and they will ooze flat, try to drive too fast over them and they will set solid..)