As ads increasingly colonize every available space (Thirsty? Grab a Coke!), USAToday reports on the latest annexed blank surface: high school tests. Oh, the children! Public places like malls, streets, and buildings are one thing, but think of the children!

With creative space-invasion in mind, BusinessWeek brings us this slideshow list of 13 creatively placed ads. Some highlights:

Ads on airplane tray tables

Ads on drinking straws

More advertising encroaching after the jump.

Ads on manhole covers

Ads on eggs

Clearly, nothing is sacred anymore, not even life. At least we still have our dreams… Or do we?