Pesterchum is an instant messaging client for fans and viewers of the MS Paint Adventures webcomic Homestuck, written by Andrew Hussie who also provided the illustrations and animations. It is the fourth webcomic in the series, which centers on a group of teens who unknowingly bring about the beginning of the end of the world by installing a beta copy of a computer game. Through the IM client, viewers of the Homestuck webcomic can communicate with one another as in a chat room. A user begins by creating a profile with a username or “chum handle”.
Users can then type their chum handle in the application to log in, and then click the color swatch to select the color of their profile. To begin communicating with other users or “pestering”, users first have to add “chums” by clicking the “ADD CHUM” button and typing in a chum handle. When added, the other user will appear on the buddy list, or “chumroll”. Users can double click on a chum to begin pestering them. Users can right-click on the handle to bring up a menu providing other options such as block and remove.
Pestering is done in a conversation window. Users are provided with messaging options, such as adding emoticons and using color tags.