Mark Duffy, aka Copyranter,  the world's most acerbic ad critic, is taking his hilarious, renegade advertising blog mainstream. After 19 years at the same small NYC ad agency, he's quitting to write the Copyranter blog full time for BuzzFeed.  "Mark Duffy here, stepping out from behind the curtain," Mark says in his first post. "I've been a New York City copywriter for more than 20 years, and I've been blogging and ranting about advertising as 'Copyranter' since 2005. Starting today, I'll be writing and ranting here at BuzzFeed, as myself. I'm 'geeked,' as you fucking insufferable young'uns say." He then gives a brief bio, relating some experiences in the ad business that are "sleazier and druggier than anything you'll see on AMC." The toughest part for the notoriously photo-averse Duffy may have been posing for the image above. Ben Smith, BuzzFeed's editor in chief, says of Duffy: "Mark's coverage of the ad industry has been provoking 'OMG,' 'WTF' and, often, 'FAIL' reactions for years, and have been all over my personal blog, BuzzFeed, and much of the Internet and the social web. He was here in spirit long before he started work, and I'm thrilled he's joining us."