my $c = 0;
$_ = "jigglewort\n";
print and $c++ while s/(.{$c})(.)(.)/$1$3$2/;

##</code><code>##

ijgglewort
igjglewort
iggjlewort
iggljewort
igglejwort
igglewjort
igglewojrt
iggleworjt
igglewortj