Copy Pasta: "Free Mini Steak Taster. Get your FREE Mini Steak Taster Wrap! Hit "get offer" for more details and to download."
Basically:
1) Share the deal
2) Receive offer in your e-mail
3) Take the e-mail to your store to claim the wrap
Pro-tip: If you don't want anyone to see the "share", change privacy settings to "Only Me" when posting. Defeats the purpose from McDonald's point of view… but you'll receive the offer in your e-mail nonetheless.
Update: Just went and picked mine up, all you have to do is show the e-mail on your phone.
hmm email is slow