Caltrop or puncture vine (Tribulus terrestris) / to thatch (a roof)
茨
=
艹
+
次
:
The King of Chu (c) wanted to pick up his cube (次) in the space station's kitchen, and he thought all he has to do is walk over sheets of artificial lawn (艹). In reality he mistook a pad of caltrop wine (茨) for the artificial lawn and soon has a lot of caltrops sticking in his feet.
next in sequence / second / the second (day, time etc) / secondary / vice- / sub- / infra- / inferior quality / substandard / order / sequence / hypo- (chemistry) / classifier for enumerated events: time
次
=
冫
+
欠
:
Mnemonic symbol: the cube, as in words involving 三次 relate to "cubic equations" or "cube (third power)". The King of Chu (c) pulls a popsicle (冫) out of the cube (次) in the space station's bathroom (Ø4) and leaves an IOU note (欠) on the cube.