At the start of Chapter 10 you'll be replenishing yourself and waited on by Augus' assistance.
1. When you're given prompts to choose from you'll want to look to your left, a giant statue will slip and fall.
2. Looking to your left, a tiny minion will dive underwater and drown.
3. And looking above at the cliff 3 separate times will expose the last of the peeping toms and earn you this 15G achievement.