"thhheeee good boyy" should be "t(hhh)(eeee) g(oo)d bo(yy)"

In that case, maybe you want something like this:

#!/usr/bin/perl -w
use strict;

while (<DATA>) {
    chomp;
    $_ =~ s/(\w)(\1+)/\($1$2\)/g;
    print "$_\n";
}

__DATA__
thhheeee good boyy
the qqquick brrrowwwn fooox
[download]

Output:

t(hhh)(eeee) g(oo)d bo(yy)
the (qqq)uick b(rrr)o(www)n f(ooo)x
[download]

Cheers,
Darren :)