Robert Rauschenberg erased his buddy Willem de Kooning's drawing. It's amusing, and I first saw it a few years ago, but I didn't really become interested in commentary on it until NPR recently featured the work in a discussion on nothingness. 'Erased de Kooning Drawing', 1953, Rauschenberg.
Digitally enhanced infrared scan of Robert Rauschenberg’s 'Erased de Kooning Drawing' (1953) showing traces of the original drawing by Willem de Kooning. Visible light scan: Ben Blackwell, 2010; Infrared scan and processing: Robin D. Myers, 2010