Drush command has unclear documentation

I think the documentation of the drush commands are rather unclear. For example; the basic example given drush zenophile foo_t "A great theme for Foo!" returns -bash: !": event not found in my OSX terminal. Giving the command without an '!', such as drush zen theme_test "the description" returns Human name field is required.

Only when adding the --friendly parameter (which in the --help is said to be optional) such as drush zen theme_test "the description" --friendly "Theme Test" is a subtheme created.