GupGupGuppy

I was watching a play through of Stick of Truth by Pewds and it made my decision for me to purchase the game. One of the major selling points was the humor including the random farting you can do. I know he was playing on a PC and I bought it for Xbox 360 but I cannot figure out how to do it and it's cutting away from many of the dialogue lines I want to hear. i'm not referring to the attack farts but in the video you will see him just fart as if it was an attack button. Any one know what I'm doing wrong? I'll post the link to the video I'm referring to the thing I'm talking about is at 5:03 seconds in to the video.