I found this description in the PhD thesis of Crystal Bennes:

Despite months of searching online and making requests for a copy of the image from those present at the talk, the image exists in description only. In a 2016 Science magazine article on the likelihood of Barish’s winning the Nobel Prize for physics in 2017 (which he eventually did), journalist Adrian Cho describes the image as ‘a man writing on a woman’s bare back and, next to her, a stage prop in the form of a cartoonish racial caricature’. On Twitter, the photograph has variously been described as featuring ‘blackface and bikini-clad girls’ and ‘a horrible racist/sexist slide featuring blackface’. Although one can easily conjure up a photograph from any of the individual descriptions, it is rather more difficult to imagine a single image which includes all of them.

Yet after spending much time attempting to source the image used by Barish, it occurred to me that, in many respects, the fact that I could not locate the image was almost more interesting than if I were able to find it. While the sexist and racist undertones of the image speak to Barish’s individual inability to comprehend its inappropriateness, the fact that I was unable to obtain a copy of the image through my professional and social networks in the physics community hints perhaps at that community’s tendency to pull together and close ranks in the face of potentially explosive press for one of the field’s leading lights. [...] Eventually, after many months of emails to different people in my physics network, I was able to obtain a copy of the image. The image was provided to me on the sole condition that I did not reveal who I obtained it from.

This reminds me of the time a few years before that when Didier Sornette illustrated his conference-talk slides with mudflap women silhouettes.