What can make a hippopotamus smile?

What can make him walk for more than a mile?
It’s not a party with a paper hat.
Or cake and candy that will make him fat.
That’s not what hippos do!

Some smiling hoppos in this. Maybe the song does it:

Or you can try this book:

http://www.shop.com/+-a-Hippopotamus+smile-p33515637-k36-st.shtml

Take him to The City of Light:

http://www.scils.rutgers.edu/~fturner/hippo.htm

When I want to make him smile, I tell him that my whanger is bigger than his.
When I want to make him cry, I show him.

I hear that hippos are actually nasty, mean-spirited creatures.

No, you’re thinking of Ms. Montoya.

Show him your belly button.

Pumpkins can make a hippopotamus smile

However, if yours takes offense at your offer of squash, remember these immortal words:

…and two hippos, who are incredibly fat. (:38)

“Flavio, are we actually fat?”

“No, my Delectable, we are simply bigger than life itself.”

Mud might do it.

Flanders and Swann