This promotion: "Candy Crush has teamed up with American Express to give lucky Facebook users $100 gift cards", is a scam. If receive this post on your Facebook Wall or Timeline, please report it as spam. This fake post will try to trick you into installing a malicious Facebook application.
The Costco Free Gift Cards and Candy Crush Promotion Scam Facebook Post

Candy Crush $100 Amex Candy Crush has teamed up with American Express to give lucky Facebook users $100 gift cards. Get yours now by clicking the link! NOTE: You must allow the app. hxxp://is.gd/vGDcs0
Costco FREE $500 giftcards (Limited Time Only!)
As part of a special promotion Costco has teamed up with Candy Crush to give away FREE $500 giftcards to all Facebook users! To get your card all you need to do is click here hxxp://on.fb.me/15EwMGp and allow Candy Crush! limited time only
---
Please do not 'like’, comment or share this Facebook post. And, if you have already installed this malicious Facebook application, please click the link below for instructions to remove it and other Facebook applications.
How to remove Facebook Applications
If there are other Facebook applications that you are not familiar with, please remove those also.
The scammers behind this scam, may change the images and the wording of this post, so please look out for similar scams.