Triple Laser
Chamber 20, otherwise known as Triple Laser, is a last test of 4th chapter containing three lasers which the player has to direct through a portal diagonally and perpendicularly into the three corresponding catchers. The test itself has almost every panel portal-able, and is the first test of the Clean theme. The test begins with GLaDOS making a remark about the completely restored function of the facility.
This chamber became very popular in community, mainly by Krzyhau, Ritbulau, Hambrix. They made a videos about that chamber, where they edit the chamber on comedic purposes. This videos title mainly start with "guys something is wrong with my test chamber", "guys something is wrong with ..." As of 3/18/21, there are approximately 56 Triple Laser variants created by various individuals. (At least 55% of which are by Krzyhau.)