plastic toy hammer, with a bellows-like head that squeaks when striking something

(onomatopoeia) digital beeping, as of a game console or chiptune

play, amuse oneself, enjoy oneself / spend one's time idle, do nothing / for an item not to be in use, be spare or idle

hammer (tool)

child

sledgehammer

child's naive mind, child's juvenile mind

plural of 子供: children

(offensive, Internet slang) a man whose age is greater than about thirty or forty who lives in one's child room and with one's parent(s).

(figuratively) being carefree and unaware of an imminent danger