In upland Southeast Asia, the internal reproduction of society by ritual is fuelled and changed through its relation to external ritual systems like Buddhism. Rmeet (Lamet), a non-Buddhist upland population in Laos, regularly alter their rituals when Buddhist lowlanders are present. In particular, the display of spilling the blood of sacrificial animals is suppressed. One recurring reason for this is the notion of 'shame' or 'fear of exposure'. Thus, the notion of 'shame' functions as a semantic operator that indicates the shifting of boundaries between inside and outside, Rmeet and lowland ritual systems. It also addresses how the border between these two ritual domains historically became defined by blood-spilling. The argument is based on a new approach to ritual change that considers rituals as information-processing systems.