All you need is a facebook account with a valid email, and yes you can exploit this for multiple uses with different email addresses and accounts or accounts of friends.
Reports from various users inform me that if you live in the United States all you have to do is simply select United Kingdom as your region when you’re entering the competition. Then the code you receive will then work on your US PSN account!
It may take a day or two or a few to get your email.
P.S. It's my first time posting on Reddit, so bear with me, thanks!
*Edit: You can try this
and select the first link.