Please familiarize yourself with the quoting rules in Perl. All of the following work as well:

$body =~ ss<img(.+?)="Wink">s;)sg;
$body =~ s$<img(.+?)="Wink">$;)$g;
$body =~ s,<img(.+?)="Wink">,;),g;
$body =~ s[<img(.+?)="Wink">]\;)\g;
$body =~ s}<img(.+?)="Wink">}{;)}g;
$body =~ s&<img(.+?)="Wink">&;)&g;
# .. ad nauseam
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Makeshifts last the longest.