I've seen a superior pattern employed elsewhere: a "grab code" hyperlink on the label of the promocode's text input that brings up a modal or opens a new tab th

I've seen a superior pattern employed elsewhere: a "grab code" hyperlink on the label of the promocode's text input that brings up a modal or opens a new tab that promises a 10% (or similar) discount in return for sharing on twitter/facebook etc. It can solve two problems - people looking for promocodes can find that tab instead of websites that show your promocodes while redirecting users to your website with their referral link, AND your website will get a bit of free publicity.