This outdoor ad from Sweden uses some technology to transcend the limits of a billboard. Apotek, a pharmacy brand, outfitted subway platform ads in Stockholm with sonic sensors that know when a train is coming. The ad will feature a model with a lush mane and when the train comes, her hair gets flapped in the wind and she struggles to keep it in place.

The tagline: Make your hair come alive. Pretty brilliant. Check it out in the video after the jump: