A non-Newtonian Fluid is a weird substance which is somewhere between liquid and solid and has properties of both. It's lump and solid and goopy and odd.
No, it's not quite as odd as the fact that the two gents known as the SlowMoGuys have built an entire career, and are now plastered on posters around the Tube, on filming stuff in slow motion.
But it's close. Check out their new exploration of this weird stuff in the video above (and Discovery's own attempt, six months earlier, below).