Spontaneous human combustion at a porn shop?

A fellow was hospitalized last night after catching fire inside a private video booth at a San Francisco porn shop. How the fire started remains a mystery. What do you think? Crack pipe and blow torch lighter? Poppers and a cigarette? Spontaneous human combustion? From CBS Local:

Police officers across the street from the porn shop saw a man run out the front door of the store "engulfed in flames," an SFPD spokesman said.

Some firefighters who happened to be about a block away at the time were immediately summoned and extinguished the flames.

"Man 'Engulfed In Flames' At San Francisco Porn Shop" (Thanks, Loren Coleman!)