Note: Thixatropic compounds, by definition, behave as if they are solids (technically "semi-solids," but think "solid" as in "solid ground" and you'll be on the right track) right up until the point that a kinetic shock disturbs the compound, at which point it flows like shaken ketchup.

Ketchup is a favorite example. Pounding on the bottom of the upended bottle when it won't pour will ensure that it suddenly pours very, VERY quickly. Pounding on the bottom while wearing white clothing or anything expensive will ensure that the bottle will expectorate more than 50% of its contents in one go.

More to the point, certain 21st-century terran cities, including Mexico City and Anchorage, Alaska, were built on thixatropic ground. Earthquakes there tended to be very destructive, with buildings bouncing around as if they were built on jiggling gelatin. The parable of the foolish man (whose house was built on the sand) and the wise man (whose house was built on the rocks) could quite naturally have included the uninformed and very unfortunate man who was careful to not build on the sand but who wouldn't know the meaning of the word "thixatropic" if you wrote it on a bottle of ketchup and poured it over his necktie.