my @tests = (
"How bout them cocks?",
"I'm a big cocks fan",
"I love the cocks",
"That cocks game was sweet",
"Anyone know the cocks score from last night?",
"gamecocks rule",
"I love the gamecocks, but...",
"My favorite cocks player is..."
);

foreach my $s (@tests)
{
    if ($s =~ /
    (?<! \b a )
    (?<! \b the )
    (?<! \b them )
    (?<! \b game )
    (?<! \s )
    \s* cocks? \b
    (?! \s fan )
    (?! \s game )
    (?! \s score )
    (?! \s player )
    /x)
    {
        print "Vulgar: '$s'\n";
    }
}