Happy hippo: Jay Parker, 35, gets a rare moment with Otis at San Diego Zoo
There's an old campfire song that asks the question 'What can make a hippopotamus smile?'.
The singalong poplular with scouts and girl guides across America suggests that hippo happiness is not down to 'a party with paper hats, or cake and candy that makes him fat'.
And it's clearly not. In fact, it seems all it requires to bring the beautiful best out of the three-tonne beast is a camera and an IT consultant.
This amazing holiday snap of the beaming behemoth was taken at San Diego zoo by Lauren Parker, the wife of Jay Parker, who is pictured alongside Otis the happy hippo.
'We took the picture on holiday at San Diego Zoo, my wife is a big fan of animals so we always try and visit somewhere when we are away,' said Mr Parker.
'Actually the week we were there the zoo had just put two hippos together for the first time in the tank.
'Hippos are not usually that friendly and the two they had in the tank - the male Otis and the female Funani - had been having a bit of a fight with each other that day.
'The hippo behind me is Otis, when we saw his face we just thought we had to get a picture.'
Mr Parker said he wasn't sure if Otis was happy or not after his day's ordeal with Funani - in fact he might even have been asleep.
Second snap: Otis was so comfortable with the camera he also posed for a picture with Lauren Parker
He said: 'If you look at Otis's back you can see the scaring from his fight with Funani, this is normal hippo behaviour but I don't think he won.
'When I look at his face I think he looks pretty tired by it all, or maybe he's having a happy dream - either way it's a great picture.'
To add another dimension to the memorable snap, the picture has become something of an internet hit and pops up on blogs and chatrooms from USA to China.
Mr Parker, 35, from Little Rock, Arkansas, even gets fan mail from people telling him he is their computer screensaver or Facebook profile picture.
He said: 'It's kind of strange to think there are people out there with a picture of me on their computer, but I guess I'm just the hippo man as far they're concerned.
source: dailymail