Yoda first appeared in Star Wars: Episode V - The Empire Strikes Back in 1980, voiced and puppeteered by Frank Oz, and his teachings about the dark side became central to Luke Skywalker's training on Dagobah. Lines about fear and anger leading to the dark side have been quoted for decades, then clipped and reused as memes and reaction sounds online. The contrast between the tiny, calm teacher and the grave warning keeps the reference instantly understood, even by viewers who have not seen the films recently.