This is a list of popular memes in the fandom for South Park.
Caramelldansen features character(s) 'bouncing' their hips from side to side while opening and closing their hands above their head in time with the beat of "Caramelldansen" by the Swedish Europop group, Caramell.
A couple editions featuring South Park exist (most of them flashes on DA). The most popular and iconic can be found on YouTube and was created by user ODENTAMAGO. What makes the video unique is this video features a wide variety of characters (including Matt and Trey themselves) and features them in South Park style compared to anime style or the type of style normally used in the Caramelldansen videos.
Get Down (Jap: ゲッダン) is a Japanese meme that originated from a glitch in the N64 game Goldeneye, where the characters (and other objects) would suddenly start "spazzing out" if the game cartridge was only partially inserted in the console. A member of Nico Nico Douga (also known as Nicovideo, a Japanese site that is like YouTube) uploaded an edited version of the clip featuring the 1997 JPop tune called Promise by Hirose Kohmi.
Some South Park versions exist and can be found on YouTube. Most versions feature cosplayers performing Get Down but one animated version of Kenny performing the meme can be found on both YouTube and artist's (Kamaniki) DeviantART and personal website.
Trust Me is the first ending theme to popular anime series, Durarara!. A couple of images done by Japanese artists can be found on the Japanese art site, Pixiv. Two videos are known to exist, one from Kamaniki and the other by Bji4z06kimocom, but both videos were taken down due to copyright. However, a flash version may still be found on Kamaniki's DeviantART page. The image Bji4z06kimocom made for her video can still be found on her DeviantART account.