grow some balls

(chiefly, US, colloquial, idiomatic, somewhat, vulgar) To be brave; to show some courage, especially in a situation in which one has so far failed to do so.

(uncountable, vulgar, colloquial) Masculinity, particularly strength, courage, and force of will; chutzpah; brazenness.

(vulgar, slang) The condition of being ballsy; courage.

An informal adverb meaning in a ballsy manner, boldly, audaciously, and with nerve or daring. Derived from ballsy, itself from balls meaning courage or nerve. Used to describe actions taken with impressive but sometimes reckless confidence. The vulgarity is mild in context; ballsy is widely used even in semi-formal settings and the adverbial form follows naturally. The adverb is used to describe both admirable boldness and reckless foolhardiness, with the speaker's tone rather than the word itself distinguishing the two.

An idiomatic slang expression for exceptional courage, audacity, or nerve, the kind that allows someone to do something most people would find terrifying or foolish. Typically used admiringly, though ironic applications exist. The image implies someone whose metaphorical balls are so hard they cannot be threatened or crushed. Common across English-speaking cultures in informal speech. The phrase is frequently applied after the fact to describe decisions that looked reckless at the time but ultimately paid off.