excited
伀 centers on a state of excitement or agitation. Its meaning is narrow and the kanji is rare, so treat it as a character for being stirred up or emotionally aroused.
伀 combines the person radical 亻 with 公, which may have contributed a phonetic element. The exact historical development is uncertain, and the character is rare.
A person 亻 beside 公 (public) suggests someone getting excited in a public setting, stirred up by the crowd.
For ショウ, imagine a person getting so excited they shout "show!" at a public event: show -> ショウ, and the person 亻 beside 公 is the one shouting.