From George Grosz, George Grosz: An Autobiography. Nora Hodges, trans. (Berkeley: University of California Press, 1998), p. 79—
He [a fellow art student named Kittelson] was teasing me one day at lunch about my "dandyism" and kept on undoing my brand new bow tie. I let him have fun for quite a while, kept my temper, and patiently retied the bow. Finally it was too much—my pride was wounded, the more so especially as other art students at a nearby table also started to make fun of me. With a devil-may-care smile, I asked him to stop, but encouraged by the laughing approval of the others, he continued. I was seized with a veritable Old Testament fury. I took my plate of Italian salad and emptied the entire contents on his head. Hands shaking with rage, I gave his head a powerful massage. It was a real Fratellini clown scene, and now the laughter and approval was on my side. My roguish friend, quite disconcerted by this unexpected shampoo, stepped lively to the men's room.