A two-party cuck is a person who is either voting for Hillary Clinton (Democrat) or Donald Trump (Republican) or someone who tries to coerce/manipulate other people into voting for the Democratic candidate or the Republican candidate telling them that voting for a third-party (Gary Johnson or Jill Stein) is a "wasted vote".

when you've done something so cringe you can't stop replaying it in your head and it stops you from getting on with your every day life