Do you honestly think that your friends care? How many of your friends are interested in becoming pirates? AT MOST, there probably aren't more than 10. You've just annoyed 790 of your friends. Some of them are your colleagues, some are your clients. All of them didn't care to receive that message.
Social Spam doesn't just come from Spammers. It comes from friends, and it comes between them.
Oauth on Twitter, friend invites on Facebook, chain mail... think twice before you share it. If someone asked you to call all your friends and invite them to become pirates, you wouldn't do it. Even if you love pirates.
Think before you share. We love you, and we'd love to hear from you, we just don't care about Pirates. So please, only invite and share with those who you believe care to hear about this from you.
Please go ahead, be a Pirate. Enjoy it. Just keep it to those who want to hear about it.