世外桃源

世 = 廿 + L : Mnemonic symbol: the WTO or WHO.

Sherlock Holmes (sh) is cleaning a flower pot (廿) under the shower of the space station's bathroom (Ø4) with a loofah (L) because he didn't quite understand a poster next to the shower from the WHO (世) explaining dangers arising from different germs.

In this case, L is for loofah.

外 = 夕 + 卜 : There's a hole in the wall of the airplane's bathroom (ai4), and from outside (外), a bat (夕) wants to enter. Willy Walrus (w) is very afraid of bats, so he does his best to hinder the bat from entering with a voodoo staff (卜).

桃 = 兆 + 木 : A few vultures (兆) cast an eye at Tecumseh's (t) Christmas tree (木) in the aorta's kitchen (ao2). To keep the vultures at bay Tecumseh throws peaches (桃) at them.

源 = 原 + 氵 : The origin (源) of the H bomb can be traced back to when Yu the Great (yu) once forgot a lot of water bottles (氵) next to her A bomb (原) in the anthill's kitchen (an2) and accidentally detonated the bomb.