My foible, a silly little simple thing it is too, is that I can easily cross my wires when dealing with HoH's. If I have:

my %families = (
                desilu => {ricky => 'lucy',
                           fred  => 'ethel',
                          },
                bedrock => {fred   => 'wilma',
                            barney => 'betty',
                           },
             );
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... every now and then I go insane and try to dive in with:

  my $whiner = $families -> {desilu} -> {ricky};
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It's not really a habit, but if I do it once in a project, I do it many times. So I'm very good friends with Data::Dumper::Simple.