When you shit out your dick hole. Dark Cum only comes out of your dick when you are jacking off and feel like you have to shit. When you feel like you are cumming, you look down and see mysterious chocolate liquid coming out of your dick. This mysterious chocolate liquid is really Dark Cum. Dark Cum usually occurs after eating lots of Chinese food.
Grant got super horny and started jacking off to a naked chick named Brooke making chocolate sauce. After jacking it for about three minutes, he thinks he is about to cum. He looks down and sees a mysterious chocolate liquid coming out of his dick and screams,"Shit! Dark Cum is going all over my leather assless chaps!"