Oobleck is weird, non-Newtonian goop. Made of roughly 2 parts cornstarch to 1 water (and in this case some orange coloring), the substance acts like a solid when hit and flows like a liquid when poured. How does it react when struck by a golf ball? Take a look:
Look at that goop shatter like a Death Star! And here’s what it looks like when a golf ball hits a balloon full of water:
Pretty neat! Besides entertaining backyard hijinks, research into oobleck and its shear-thickening relatives has provided better body armor and space suits.
In the meantime, enjoy this video of oobleck riding a chainsaw, eating a BB, and catching an explosion. Enjoy!