Nasty smells I have known (all chemical, I'm afraid). Phenyl Acetic Acid; some people say it smells of honey, some say it smells of pee. Butyric Acid; smells of sick and rancid butter (doesn't last too long though). iso Valeric Acid; smells of sweaty socks. para Menth-8-thiol; cat's pee. Sulfurol; smells of hot milk (which I can't stand). Isofreshal or Maceal; speciality chemicals which smell (to me) of rotten milk. Doubt if you will be able to get any of these by tomorrow though.