Clapping Party

From Homestar Runner Wiki

Clapping Party a video game, originating from the Strong Bad Email slumber party. It's objective is to clap hands on the screen together by clicking a button beneath them. Doing so three times will result in a screen saying "Round Clear!". On the second round, clapping three times unlocks Blistergeist mode. This will make a ghost with a mask and a chainsaw produce bad blisters on the hands onscreen.

Clapping Party is the only game Homestar is allowed to play.