互不相欠

互 = 一 + 彑 : Helga Horse (hu) is freezing in the space station's bathroom (Ø4). She rubs her two front hooves mutually (互) against each other to warm up a little. Even her wet snout (彑) is frozen: she cannot play the flute (一) anymore.

不 = 丆 + 卜 : Bruno Bear (bu) is setting up a wind wheel (丆) with a voodoo staff (卜) in the space station's bathroom (Ø4). He also puts a "forbidden" sign (mnemonic symbol for 不) on it, to make clear that it may not (不) be stopped.

相 = 木 + 目 : I take "eye" and "tree" as resembling an ent, an alive tree. Marie Curie portrays an ent in the anglepod's bathroom. Unfortunately she's really bad at painting, and her portrait resembles more a Christmas tree. The Eye of Providence enters and, just from the shape of the Christmas Tree, instantly recognizes its own portrait. The Eye of Providence asks Marie Curie how much she wants to have for the painting, but Marie Curie just wonders if the Eye of Providence is made from Radium, because it radiates so much.

欠 = ⺈ + 人 : The Queen of Hearts (qi) is pretty annoyed by Neanderthal Man (人), who is quarreling with the crane (⺈) in the anthill's bathroom (an4). Neanderthal Man (人) owes the crane money, and the crane is waving with his IOU note (mnemonic symbol for 欠).