If you've not used Snapchat, you may not get these ads. And that's perhaps part of the point.
The social app allows anyone to design and upload so-called 'geofilters'—overlays for your snaps—that typically represent the location where the photo or video was snapped, among other things. Snapchat has taken these geofilters and put them on billboards in specific locations, examples of which can be seen in the link.
The ads feature no logo at all (a cue from the preference for subtle branding in social media advertising on platforms like Snapchat and Instagram?), betting on the geofilters and the trademark Snapchat yellow being ownable enough, despite the fact there are literally hundreds of them and they all differ in style. And it's probably a smart omission—the app has developed something of a passion brand among its users. If you use Snapchat, you get it, logo or no logo. And if you don't, your wondering what the ads are all about… so they've got your curiosity.
I also like how the real-life geofilters work in the same way as the pixel versions to label the area in a funky way. I can't believe I just said funky, but this is a great example of taking online ideas offline.