Verb
grow a pair (third-person singular simple present grows a pair, present participle growing a pair, simple past grew a pair, past participle grown a pair)
(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.
At this, even Hillary Clinton was thinking, "Come on, guys - let's grow a pair." Ann Coulter