When we hear the expression ‘set someone on fire’ we normally have in mind a passionate, intimate picture, charged with sexual energy, but in the particular case of setting ourselves on fire, this might get weird and even deadly. I’m not sure if you’re familiar with the case of Grace Pett, an elder woman who lived in Ipswich, England (pretty close to my university) in the 18th century. If you are interested you can google her name and find out more about her story, but to make it short… she just went to bed one night and in the morning her daughter found her body like “a log of wood consumed by a fire, without apparent flame.” (1) Except the Bible…which is up to you whether represents or not a valid case, this is on the first documented examples of spontaneous human combustion. This is characterised by the incremation of the human body, without any type of external fire. When investigating the phenomenon, the scientists tried to blame it first on external factors, but in the genuine cases, the furniture positioned in the close proximity of the person were not altered. One possible explanation could be the interaction between the (incredible amount) of alcohol consumed by the individual and an external source of fire, but this doesn’t apply in every case.
References: (1) http://www.crystalinks.com/shc.html