It started as a quote in Maximo Ramos’ The Aswang Complex in Philippine Folklore. Ramos was explaining how rural Filipinos often prefer to sleep on the edge of the room, rather than the middle, for protection against the viscera sucking version of the aswang — the kind who climbs on the house and drops its tongue down between the chinks of the roof to suck out its victims innards.
Sleep towards the edge of the room, Ramos warned, but not too near a post:
for the posts may harbor a tree-dwelling mythical demon like the bangugot or batibat. This is a nightmare-inducing, insanity-causing creature resembling the genii of the Near East. It is said to have refused to leave its tree when it was felled and stubbornly to have gone on living in a crevice of cavity in the wood, emerging to sit on a tenant’s chest and suffocate him by plugging his mouth with its phallus and his nostrils with its testicles.
Huh. That deserves more investigation, I thought.