When I first saw this thread in Newest Nodes, I misread it as

perl T-shirt and #!/usr/bin/perl -T conflict

(I'd recently seen jima's note about the nifty Camel T-shirt, and probably hadn't had enough sleep.)

But I wonder, doesn't a t-shirt that reads

#!/usr/bin/perl -w
use strict;
[download]

cover only two of the four most common bits of advice handed out here? Wouldn't a truly monastery-compliant t-shirt begin

#!/usr/bin/perl -Tw
use strict;
use CGI;  # don't reinvent the wheel
[download]

And then, on the back

(*)++  ( )--  ( )+= 0
[download]