Yarn vomit, also called yarn barf, is a term used in various yarn craft online spaces. It often refers to when someone attempts to pull just the center strand of a yarn skein, and in the process pulls out a large chunk of messy yarn. It can also be used in reference to any highly messy and tangled length of yarn.
"I was excited to use this yarn, but it's just become such an unworkable pile of yarn vomit. I don't think I could untangle it with a month of work."
Yarn chicken is a term often used in online knitting/crochet circles. It is a self-imposed 'game' in which a crafter is unsure if they have enough yarn in a skein to complete a project, but rather than going through the process of measuring and weighing to find yardage, they start the project and hope it's enough. The crafter wins the game if they finish their project with just enough or extra yarn, and they lose if they run out of yarn before completing their project.
I'm going to go pick up some yarn. I lost Yarn Chicken and I really need to get this hat done.