When I was doing this, the guides were mostly for xbox. They were talking about controllers and stuff. I had to research for a while.
If you are playing the game on pc. Here are the keys.
"You can get this in mission 11, Captive. When you are taken to an interrogation room with Barkov. Beginning at your first dialogue choices, press both same time your left + right mouse buttons and you can spit on Barkov's face. Your achivement will unlock shortly."