Body scanner (DeepNude) is a simulation of undressing people using mobile phone. Application adds half naked pictures on top of selected photo. This way it looks like a virtual intelligence undressed your friend and show his/her body. Of course it's just a prank so you need to take a proper photo of your friend and add the naked body layer. You can tell your friends that this app is called DeepNude as this is an app which shows people without their clothes.