Walnut Sauce is when someone's pineal gland is removed and possibly consumed.

Your pineal gland, also called the pineal body or epiphysis cerebri, is a tiny gland in your brain that’s located beneath the back part of the corpus callosum. It’s a part of your endocrine system and secretes the hormone melatonin. Your pineal gland’s main job is to help control the circadian cycle of sleep and wakefulness by secreting melatonin.

Isaac recorded several "strange" videos where he's clearly trying to get a message out to the public about what's REALLY going on in Hollywood. He had a very suspicious death where he allegedly threw himself off a bridge into traffic very early in the morning. There were reports that people were with him trying to "help stop him" but he fell anyways.