The Surprising Moment From Last Episode's Mad Men --

Last night's Mad Men took a real turn there at the end. 

Ginsberg, increasingly freaked out by the new office computer and (surely) the multiple 2001: A Space Odyssey references swirling around the office, "released the valve" by ... cutting off his own nipple. Then he gave Peggy the remnants.

 see it here:
The Surprising Moment From Last Night’s Mad Men -- Vulture