You might be familiar with Non-Newtonian liquids if you ever used to mix together corn starch and water to play with as a kid. Water and corn starch look like a liquid but when you touch the mixture it feels like a solid.
That's because Non-Newtonian liquid particles are really big (at least as far as particles go). As the video above explains, when the particles are disrupted, for example if someone punches the mixture, they don't have enough time to move as a Newtonian liquid would, so they become solid.
You know what's even cooler than watching someone punch a Non-Newtonian liquid? Watching someone punch a Non-Newtonian liquid in slow motion! Watch the video above to see some slow-motion Non-Newtonian liquids in action.