An anthropologist was assigned to Borneo, where he found a guide with a canoe to take him up the river to the remote site he where he would make his collections. At noon on the second day of travel up the river they began to hear drums.
"What are those drums?" asked the anthropologist, knowing he was in cannibal country.
The guide turned to him and said "No worry. Drums OK, but very bad when they stop."
They both went ghostly pale when the drums suddenly stopped. The guide crouched in the belly of the canoe and covered his ears.
"Do as I do! Very important!""intoned the guide with great urgency.
"Why? What does this mean?" asked the panicked anthropologist.