In some parts of the world, people smoke cigarettes by holding the lit end inside their mouth. Apparently this doesn't burn them. In fact, reverse smokers claim that they enjoy the sensation of warmth it creates inside their mouth.
Journal of the American Dental Association - Mar 1976
Because reverse smoking has long been suspected of causing various dental problems, the most complete analyses of this habit are found in dental journals. I thought this discussion of it from a March 1976 article in the Journal of the American Dental Association
contained some particularly interesting bits of info:
The cigarette-smoking habits of people in some parts of the world include a variation called reverse smoking, which is accomplished by holding the lighted end of a cigarette or cigar inside the oral cavity. Air is drawn to the burning zone through the unlighted end of a cigarette, and smoke is expelled back through the cigarette or out through the mouth. The smoke is not usually inhaled; however, the ashes are swallowed. Smoke and tar products are allowed to condense on the surfaces of the teeth, palate, and adjacent mucosa. Tobacco tar and smoke that come into contact with the highly vascular moist mucosa contribute to the pleasurable sensation.
Reverse smoking has been reported to occur in the lower economic groups in areas of India, the Caribbean, Sardinia, South America, Korea, and the Philippine Islands. In the Philippine Islands, reverse smoking is referred to as “ bakwe” and is practiced almost exclusively by married women. It is a symbolic indication of the achievement of marital status and represents the responsibility that is peculiar to a married woman, in contrast to the carefree life-style of an unattached maiden. Many look on an unmarried smoker as a woman of easy virtue.
It is noteworthy that in parts of Korea women begin smoking on their 60th birthday, to represent the beginning of their retired life. This signifies wisdom and experience.
Motherhood and housework are the primary reasons why reverse smoking is practiced only by women. It enables the mother to feed and tend to her child without the risk of the infant touching the lighted end of the cigarette. It also eliminates the possibility of ashes dropping on children, eating utensils, clothing that is being washed, and food that is being prepared.
Reverse smokers give several other reasons for indulging in this peculiar habit: it is more pleasurable than conventional smoking; it gives one the feeling of warmth during the rainy season (This may explain why reverse smoking is practiced primarily in equatorial climates, which usually have a long rainy season.); there is no desire to inhale; and the cigarette or cigar lasts longer.
A study by Quigley and others reported that the average time for conventional smoking of a cigarette is four minutes and six seconds, whereas the average time for reverse smoking is seven minutes 42 seconds. Native reverse smokers may retain a single cigarette for as long as 18 minutes.
Journal of the American Dental Association - Apr 1966
Heavy tar buildup inside the mouth of a reverse smoker.
Journal of the American Dental Association - Oct 1964