Eurostar is running an integrated marketing campaign in Belgium to promote its summer connection to London. The price for a two-way ticket it's 69 Euros, so the advertising concept rotates around the 69 (sex) position.
Outdoor advertising invites those who pass by to text an SMS and interact. Online ads are running to drive traffic to www.eurostar.com/londonXperience where a community game gives away tickets to London. A viral video is also part of the effort (too bad the "send to a friend" option is missing).
The agencies behind this campaign are TBWA\Belgium and Hypervision for what concerns the interactive part.
[Thanks to Bert Van Wassenhove for the hint]