Thanks for all the input, guys. I enhanced the initial suggestion to include a few more lookforward possibilities which I think covers enough bases for me to keep it in the dictionary. I omitted the dirty test cases since these are "sacred" boards, but they did get caught correctly :)

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";
    }
}
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-Darin