How to use "It's going down/about to go down" I saw the phrase "Oh shit! It’s about to go down" in a picture about two videogame mascots staring each other., I don't know if you can only use those phrases when referring to a fight or there are other situations where you can use "it's going down/it's about to go down". Can somebody explain it to me?(And give some examples)

Question about a part of this YouTube video(Smiling friends) May somebody help me? I can't fully understand this part. 1:22 "I know is our job to help this guy and everything, but I thinks this guy is a lost cause, he's obviously ________________________________________ and get out of here." https://www.youtube.com/watch?v=ZBJyNU_YlpY

What does "Make a heel of oneself" mean? Context: In the story, The main character was worried about a girl but she wanted to be alone, so he decided to follow her, at the end he find out she only wanted to give him a surprise gif. Then he said "I feel like I really made a heel of myself"