gallon, quart
呏 centers on units of liquid volume: a gallon or a quart. It is a specialized character used for these measurements.
呏 is a modern Japanese kokuji created by combining 口 (mouth, here likely indicating a unit of measurement) with 升 (a traditional measuring box for volume). The exact historical development is uncertain, but it was likely formed to represent Western liquid measures.
The mouth radical 口 beside a measuring box 升 suggests a unit of volume you might drink or pour: a gallon or quart.
For ショウ, imagine a gallon jug with a label that says 'Show' — as in, it's showing off its size. Show -> ショウ, and the jug holds a gallon.