Mnemonic symbol: a balloon. The Queen of Hearts is disappointed by her balloons. She expected them to float upwards, but in the space station's bathroom, They float randomly in all directions.
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Yu the Great (yu) wants to stick a mandarin (口) into a honey jar (于) and eat it, but in the space station's bathroom (Ø4) the mandarin is imploring (吁) him to not do it.