There was a show with Betty White where she was feeding a whole watermelon to a hippo she'd been friends with for over 20 years.

It loved her and came right up to her.

Possibly the Pet Set but I couldn't find the video all I could find was her feeding an alligator in Lake Placid (which I don't remember ever having watched).

Maybe I'm remembering everything wrong, but if not maybe someone else has that video or show in their back pocket and can help out.