Sir Adrian Carton de Wiart served in the Boer War, World War One and World War Two. In the process he was shot in the face, losing his left eye, and was also shot through the skull, hip, leg, ankle and ear that is how he got the name unkillable soldier
When you want to post something on someone's Facebook wall, but the fact that the information concerns someone else who might see deems the information un-postable on the wall, therefore unwallable.
Person 1: Dude that is HILARIOUS I need to put that on Vicky's wall
Person 2: Dude it's unwallable, Sasha's friends with her on Facebook Person 1: Dude you're so right, close call!