High-tech wallpaper keeps neighbors from stealing Wi-Fi
The only problem is that being French, the wallpaper will be in a zig-zag pattern in contrasting colours of bright blue, orange, greeen and red. Not only can't you steal the wifi, five minutes after entering the living room you have a violent migrane and can't see enough to steal anything.
This, BTW, is NOT a joke and is not insulting to the French (for whom I have great affection). It is just true.