A better way to do it:
Type !;!;!;!;!;!;!; as many times as you want, but before you hit enter place one error in what you type, like say:
!;!;!;!;!;!;!;!;!;!;;
When you press enter, it says "invalid cheat" but it still acknowleges all the !s youve entered. And after you hit ok, everything you typed is still there. So you can just hold down enter and rake in the cash!