Just in time for Christmas, a guide on how to avoid spontaneous combustion can be found at Real Clear Science's Newton Blog.
Although most cases that are thought to be sponaneous combustion -- where a human being just suddenly bursts into flames for no apparent reason -- turn out to be something else, various medical records stretching out over some 2000 years show 150 or so cases in which no other explanation can be found. In other words, those people somehow just blew up.
The problem is that a large percentage of the human body is water, and water doesn't burn well. So for a human body to burst into flame without any help, you need to work out a way around the presence of all that water. Some theories held that another liquid replaced the water, and that liquid was much more flammable. If the right conditions prevailed, then the alcohol could be the source of the burning.
But in 1851, a German scientist pointed out that bodily tissue specimens were usually preserved in solutions that were about 70% alcohol and they didn't catch fire on their own. This is good news for Daytona Beach during Spring Break and Ireland at just about any time of the year.
In a more recent experiment, microbiologist Brian Ford soaked pig tissue in acetone (pig parts are considered to be pretty close to human parts for many purposes, as any fan of Mythbusters can tell you). Acetone is also flammable and these tissues did in fact burn quite nicely. Acetone also mixes with the body's chemicals and can replace water if a person's diet or activities mess with their body chemistry through ketosis, a process that raises our level of ketones, which are acetone substances.
Unfortunately for those Spring Breakers and me auld Irish cousins, excessive alcohol consumption is one activity that can lead to ketosis. So they'd probably better pay attention to those "No Smoking" signs."