app >> code >> core >> mage >> paypal >> model >> standard.php
'cbt' => "CLICK HERE TO COMPLETE YOUR TRANSACTION",
'zip' => $a->getPostcode(),
If anyone’s wondering why it was so important, it has to do with triggering my affiliate tracking code on the order complete page. If the customer doesn’t return to the store after using paypal, the trigger won’t happen and my affiliates don’t get credit.