The keeper at the zoo in Japan said the behavior is especially puzzling since the female isn't in heat.
The two animals just seem to enjoy kissing. They have gone through the same ritual twice a day for the past 10 months.
The female was born at the zoo and met her boyfriend when he moved from another zoo eight years ago.
Keepers said the two have lived together ever since.
Image Gallery: Nbc11
Tags: Panda | Kiss