This one is a one from us that we did last autumn for Rexona Teens, a deodorant for teenagers that, being always the same product, changes its tagline every year, "Dance and teens", "Love and teens" or, in this case "Fans and teens".
To support this last one we created a little promo using a Facebook app called "Your line of fans", that allows you to show if you're a better fan than others, and you're required to create the longest line to support your favorite artist, inviting your friends to be formed in your line (and then the friends of your friends), so you could use the line to try it to be the longest and also to meet new friends that share with you the same interest in that artist.
In the end, the longest line (whoever the artist is) could get some tickets to attend some shows from that artist (looks like Jonas Brothers rule for teens) Here's a little video explaining the project: