King Hippo is one of the main boxers in Nintendo’s Punch-Out out on NES. I remember when I was a little kid, my cousin and my brothers all failed to beat him.
That’s because he has a trick to him. You have to wait for a small opening, and then you can have him. The funny thing is, you have to keep punching him while he tries to hold his pants up.
After knowing the secret, King Hippo becomes about as easy to beat as Glass Joe.