This is the hilarious moment a cheeky orangutan cracks a big smile - as he grabs a zoo worker's breasts.

The animal handler was posing with the primate in front of tourists at the Safari World Park in Bangkok, Thailand, on Sunday (25/11) morning.

But after putting his arms round the woman's waist, the male orangutan then raised his right hand and began laughing as he grabbed the woman's left boob.

The staff member, named Sunan, 26, let out a nervous giggle as the orangutan - named 'Ning Ning' - fondled her cleavage.

An onlooker is heard shouting ''he's massaging it, he's massaging it''.

Safari park worker Khun Fah, who recorded the video, said: ''Ning Nong is very cute. I think he knew what he was doing so that he could make people laugh. We told him off after and said don't do it again.''