The moment when all I can say is: WTF?!

Allright. 
This is what happened yesterday.
I was colouring the Tyrion Lannister drawing I submitted this week.
I was going to color when... 
You know, I was drawing on the cardboard, the one on the back of the sketchbook... Well.
A moment and all I created literally fell from the sheet. Well, the pencil had taken off a layer of cardboard. I'm still in shock, because it wasn't the cardboard that we use for wrapping, but the one "tough" , the one that we use to draw, sometimes... I don't know how to say in English, sorry. But I colored the entire wall treading strong and it hasn't gone bad. I rub VERY LIGHTLY the rubber on the wall in the drawing and nothing happens, but on the face? It removes a layer. And I can't draw on it again.
The silver lining is that at least I photographed the drawing step by step. Really, it's a shame. I was proud of it, by golly.
You ... how do you overcome these drawbacks?
Do you draw on cardboard? How do you call it in english, cardboard or in other ways?