Nicotine poisoning is probably one of the worst, and definitely one of the easiest, ways available to make yourself sick. Some quick words of advice on the topic: avoid this like the plague. That should be obvious, but you know - people will do anything, if it sounds interesting.
Most cases of nicotine poisoning, oddly enough, do not come about by smoking, but ingestion of tobacco, or contact with raw tobacco leaves. Generally, it is small children who suffer this malady, being more prone to both eating random things and poisoning. You would think that the horrible taste would be enough to scare them off, but apparently not. According to the Australian National Injury Surveillance Unit, between 1986 and 1991, about 23 children a year are reported ill due to eating cigarettes, and of these, about 8 require hospitalisation. People who grow their own tobacco will also often get sick in the harvesting phase of their operation, as nicotine leaches in through their skin.
Basic nicotine poisoning symptoms are as follows:
This generally expresses itself as feeling sick, shaking, breathing fast, dizziness and a horrible taste in your mouth that you can't spit out enough. Oh, and you can't see in the dark anymore.
More severe cases of nicotine poisoning will have the above symptoms, though the burning will be felt in the stomach and intestines, as well as bradycardia, arrhythmia and eventually, coma and death.
If you think you, or someone you know, is suffering from nicotine poisoning, the first thing to do is call Poison Control. Or, if the poisoning came about due to skin contact with nicotine/raw tobacco, to wash the affected area under running water and scrubbing at it with soap. Do not induce vomiting, as this is dangerous, and the patient will be doing that themselves, anyway. Poison Control will ask several questions to attempt to determine the severity of the poisoning (if your friend is convulsing, tell them to skip this bit, and send an ambulance, please), and give you directions from there. If, by some chance, you happen to have a lot of medical supplies lying around, feed the person activated charcoal, to absorb any nicotine in their stomach, combined with a cathartic if possible. It's best to do all this outdoors, or in an easily-hosed area, as well, because cathartics, charcoal and the poisonous effects of nicotine combine to produce symptoms that only a mother could love. Thereafter, try and control any convulsions and wait anxiously for an ambulance to arrive.
Hospitalisation is only necessary in serious poisoning cases, but some people will feel much better for the trip, anyway. Mild cases of poisoning will pass after a few hours, the person will be slightly weak afterwards, but otherwise fine.
In case you are wondering, one smoked cigarette butt potentially has enough nicotine in it to kill a child of the eating random things stage. An average human adult would probably die from eating two to three whole cigarettes, as the amount of nicotine in an unsmoked cigarette is about 300 times as much as you get from smoking it. A cigarette butt will also make an adult human (non-smoker) quite sick, so do not be tempted to eat one under any circumstance.