Verb (used with object) : His cruelty out-herods Herod.    From Dictionary.com. 

Simon-Pure Southerner from the very fact of their nativity, and visited with the most horrible retribution wherever they have shown a leaning toward the land of their birth, they find it necessary to out-herod.    From Wordnik.com.  [The Continental Monthly, Vol. III, No. V, May, 1863 Devoted to Literature and National Policy] Reference

(For Virgil and Nativity play and prophecy see authorities in Comparetti, "Virgil in Middles Ages", p. 310 sqq.) "To out-herod Herod", i.e. to over-act, dates from.    From Wordnik.com.  [The Catholic Encyclopedia, Volume 3: Brownson-Clairvaux] Reference

Every man’s invention seemed on the stretch, and each extravagant simile seemed to set one half of your men of wit into a brown study to produce something which should out-herod it.”.    From Wordnik.com.  [The Fortunes of Nigel] Reference

Every man's invention seemed on the stretch, and each extravagant simile seemed to set one half of your men of wit into a brown study to produce something which should out-herod it. ".    From Wordnik.com.  [The Fortunes of Nigel] Reference