醋

醋 = 酉 + 昔 : Because Kitty Cat (cu) is chasing the rooster (酉) so often it decided to take revenge. In the space station's bathroom (Ø4) Kitty Cat is about to enjoy a milkshake (昔) into which the rooster poured a good shot of vinegar (醋).

昔 = 井 + 日 : Mnemonic symbol: From 奶昔, milkshake

In former times, Marie Curie thought that at the end of every day, the sun falls into a well and therefore the light goes off. Nowadays as she is floating in front of the space station, she finds that she was right: as in the former times, every evening the sun goes into the well to fetch herself a milkshake.

酉 = 兀 + 日 : The rooster and Maud Younger are taking part in a re-enactment in the outhouse. They re-enact former times by getting up with sunrise; the rooster stands on top of the sun and crows so that everybody gets up, and Maud Younger plays a traditional sihu fiddle.