Nobody here asked, but since I just sent this in response to an inquiry elsewhere, I thought I'd take advantage of keystrokes already made:

Bearding the lion = to be uncommonly and rashly brave; to be so courageous as to dare to seize a lion by the beard.

From the Latin, "mortuo leoni et lepores insultant," and hares leaping at dead lions. Shakespeare, in King John, said, "Your are the Hare of whom the Prouerb goes, Whose valour plucks dead Lyons by the Beard" quoting perhaps from Thomas Kyd's The Spanish Tragedie, "Hares may pull dead lions by the beard."

- per Charles Funk in A Hog on Ice.