问世

问 = 口 + 门 : Willy Walrus sees a mouthwatering mandarin hanging over a door in the floor of the encampment's bathroom. He asks himself: "is it a trap?"

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.