The best way to do this generally is to pass in an anonymous sub which executes the sub with the desired arguments e.g

sub print_me {
  my $arg = shift || "Hello World!\n";
  print $arg;
}

%hash = (
  no_arg   => \&print_me,
  with_arg => sub { print_me("Hello World, again!\n") },
);

$hash{no_arg}->();
$hash{with_arg}->();

__output__

Hello World!
Hello World, again!
[download]

Also, you want parens, not curly braces when assigning to a hash as curly braces will return a single element of an anonymous hash reference, whereas using parens will return a list (in this case) which will duely populate %hash. See. perlreftut and tye's References quick reference for more info.
HTH

_________
broquaint