To apply a command to the next singleplayer game you play, click the paper icon on the bottom right of the title screen. A box should pop up to type in.

Commands that change the speed of the game are: fastcl fastercl fastestcl (commands below usually are the same speed as fastestcl and/or are too fast to even play with) maximumcl infinitecl

Extra/fun commands are: discofever -a crazy disco effect for every kill. heatwave -special outfit. multilobby -more than 2 people in a multiplayer lobby. it's glitchy.