This fear was shared by all, by us senators as well as by the rest. And here is another thing that he did to us senators which gave us every reason to look for our death. Having killed an ostrich and cut off his head, he came up to where we were sitting, holding the head in his left hand and in p115 his right hand raising aloft his bloody sword; 2 and though he spoke not a word, yet he wagged his head with a grin, indicating that he would treat us in the same way. And many would indeed have perished by the sword on the spot, for laughing at him (for it was laughter rather than indignation that overcame us), if I had not chewed some laurel leaves, which I got from my garland, myself, and persuaded the others who were sitting near me to do the same, so that in the steady movement of our armies we might conceal the fact that we were laughing
this just all points to Commodus being insane.