The Hippo is a much maligned creature. Forever scorned by data scientists and UX professionals.
Hi.P.P.O stands for the Highest Paid Person's Opinion. It's a time honored way of making decisions which goes back centuries.
If a decision has to be made, the boss' opinion wins. After all, there must be some reason they get paid more!
If we're deciding between a red button and a blue button for our Call-To-Action, don't test, just ask Hi.P.P.O! There's even a SaaS web site dedicated to asking Hi.P.P.Os.
Personally, I don't mind the Hi.P.P.O. Sometimes I have to bow before the Hi.P.P.O. Sometimes am the Hi.P.P.O.
What I truly fear is the Z.E.B.R.A (More on that below.)