Youtube poop or more commonly used "YTP" refers to any video on youtube that is a collection of random scenes or clips from various cartoons, shows, movies, and games. Most contain dubs and voice overs from other shows and movies to make a scene deemed "unfunny" to be "funny". Most YTPs use Mario Brothers (90s TV series) and The Legend of Zelda (CD-i game.) These are the most popular two, but many other popular shows or cartoons used in YTPs are but not limited to iCarly (Teen Show on Nickelodeon), Spongebob (Cartoon on Nick.), Toy Story (Disney Pixar), Chowder (Series on Cartoon Network), and Pokemon (Anime).
That "King gets Rick Rolled" is a Youtube poop.