The problem is this is not affiliated with Chipotle, and it's a scam. If you click on the post, it wants you to invite four friends to get their Chipotle card, too.
If your four friends click on the link, the post claims you will get your card quickly. Do not click on any links.
While Chipotle is offering free guacamole today, the restaurant is not affiliated with this gift card giveaway.