The phrase "they spit into a vial" usually refers to the act of providing a sample of saliva for medical or scientific purposes. This process typically involves spitting saliva into a small tube or vial that is then sent to a laboratory for analysis. Saliva contains DNA, and researchers can use it to study genetic factors that contribute to various diseases. Spit samples may also be used for COVID-19 testing, as the virus can be detected in saliva. Overall, "they spit into a vial" means that someone provided a sample of their saliva for analysis or testing.