View source for North Indian Popular Religion:12-Malevolent spirits

=Yawning=

Hence it is very dangerous to yawn, as two kinds of danger are to be apprehended—either a Bhût may go down your throat, or part of your soul may escape, and you will be hard set to recover it. So if you chance to yawn, you should put your hand to your mouth and say Nârâyan—“Great God!” afterwards, or you should crack your fingers, which scares the evil spirit. This idea is the common property of folk-lore.18