Portal 2 Aperture Laboratories warning text and silhouettes HD Wallpaper

Two stylized silhouettes are depicted against a smoky, textured background. The silhouette on the left is running, while the silhouette on the right is gesturing with an exclamation mark above its head, and is crossed out by a prohibition symbol. Text above reads 'IF A FUTURE YOU TRIES TO WARN YOU ABOUT THIS TEST,' and text below reads 'DON'T LISTEN.