We decided to brave it, and do a video of flour and water. The combination, forming a sticky very messy dough is one of the hardest to clean up, especially in hair. Fining small clumps of dough stuck in all places is common days after! But it was fun, a laugh and for only the second time in a recorded WAM video, myself and my husband got messy together. The only previous was mud wrestling.
It took some four hours to clean up despite having a really good exit plan, we didn't plan for two blocked drains.
So here you go... a long time requested video, just for you.
Sure looks like fun, but speaking from personal experience, I'd bet that was a real pain in the neck to wash out. I tried it once with my wife and we were still finding clumps of flour in her hair two days and 8 showers later.