The anthropomorphized versions of the Mane Six characters from My Little Pony are invited on to Friday Night Party and find themselves in a six-way gunge vote, with Rossi Lombard encouraging them to make their case for why the others should be gunged instead of them despite their show's emphasis on cooperation and friendship.
In the end, Twilight is the one who gets the most votes and is gunged by Celestia after a surprise appearance. However, Pinkie puts in a special request backstage and the gunge tank is brought out again at the end of the show to slime her as well.