http://www.netrover.com/~timt/cheats/c/clownomania.html (Amiga Plus Extra No. 5/97, 05/1997)Click both the mousebuttons on the titlescreen and push fire. Now press 'G' for infinite lives, jumps and shots.
While playing press the 'HELP' key for more jumps and shots. It won't show until you use one.