So, this is
Flag, the Jasper Johns' painting I was referring to in my second question. Johns did several other versions of it, but this one was the first to be exhibited in 1957, and it looks like it startled the art world at the time: Alfred Barr of MoMA wanted to purchase it but he was afraid that it might be seen as unpatriotic by his board, so he arranged for someone else to buy it and later donate it to the museum.
As for the title of this post, it's a reference to the work of Jake and Dinos Chapman who defaced three paintings done by Adolf Hitler when he was young. These pictures initially featured gloomy landscapes, vistas of Roman Ruins and still life; the Chapmans added light, rainbows and psychedelic colors. It's an interesting case of defacement, since no one really knew about the existence of these paintings before (apparently Hitler did them when he was trying to enter art school in Vienna), nor was anyone eager to defend them as works of art that deserve respect, after the Chapmans brought them to light.
So here they are:
Some serious "psychedelic goth", ain't it ?