硬化

硬 = 更 + 石 : Maud Younger (y) finds the snake which ate too much (更) in the engine's bathroom ((e)ng4), and it feels miserable. To make the snake feel better Maud massages the snake using two warm stones (石). As Maud massages the snakebshe finds that the snake's belly is really hard (硬).

化 = 亻 + 匕 : Helga Horse and Rosa Luxemburg conduct an experiment in the ashram's bathroom. Using a transformer, they melt a ladle.