YouTube Lightsaber
The red and green bar under a YouTube video that shows the number of likes (green) and dislikes (red) which closely resembles a Lightsaber from the Star Wars films. More green than red makes it resemble a Jedi Lightsaber and more red than green makes it resemble a Sith Lightsaber.
So many people dislike this video that the red YouTube Lightsaber looks like Darth Vader's Lightsaber.