Tried posting this, got rejected for a spoilery icon, so I'll stick with my default icon this time around.
So, Portal is free for PC and Mac until the 24th (
http://store.steampowered.com/freeportal/), so I've been playing through it again, and it reminded me of something.
Images from/spoilers for Flesh and Stone.
Also, in a similar vein,
You'll forgive me for the lack of fancy photoshop on the last one.