What is the unhealthiest thing to smoke?

Could you elaborate on what you mean by "unhealthiest thing to smoke"? Are you referring specifically to tobacco products, or are you open to considering other substances that may be smoked? In general, smoking any form of tobacco, including cigarettes, cigars, and pipes, is widely recognized as highly detrimental to one's health due to the harmful chemicals and carcinogens present in the smoke. However, if we broaden the scope to include other substances, the answer may vary depending on the specific compound being smoked and its potential for harm. Is there a particular type of smoke you're curious about?