The word "泡蘑菇" is formed by directly combining the verb "泡" (meaning to soak or immerse) with the noun "蘑菇" (meaning mushroom), creating a metaphorical idiom. It draws from the culinary step of soaking dried mushrooms, which requires time and patience, to analogize a person intentionally delaying or dawdling in a situation, thus conveying the meaning of procrastination or wasting time through persistent lingering.