硬木

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).

木 = 八 + 十 : Mnemonic symbol: a Christmas tree.

Malte Monkey (mu) is setting up a Christmas tree (木) in the bathroom of the space station (Ø4). He decorates the tree with eight-balls (八) and puts a holy cross (十) at the top of the tree.