when the stock market crashed on black thursday oct 25 1929 30 billion was quickly lost that amount was twice the u s national debt at the time some 20 000 companies went bankrupt which left many investors with a lot of worthless paper 
those lucky enough to avoid homelessness used the now worthless stock certificates to paper their walls an old technique used to plug drafts before insulation was widely available or used others may have sardonically pasted the worthless certificates to their walls as decoration now wallpaper is used to describe any security that has lost all value even if there is no longer a practical use for it 