锈
=
钅
+
秀
:
Marie Curie (xi) is demonstrating in a talent show (秀) in the outhouse's bathroom (ou4) how she can magically remove the rust (锈) from a golden harpoon (钅) by dipping it in the toilet. Her secret is that she poured the right chemicals in the toilet earlier.
a "screw that never rusts" — sb who selflessly and wholeheartedly serves the Communist Party, like Lei Feng 雷鋒|雷锋[Lei2 Feng1], to whom the metaphor is attributed