A high-steaks competition involving an amoosing photo of two cows eating ‘grass' has surfaced online.

Waikato District Police are asking members of the online community to caption a photo of two cows munching down on several cannabis plants in a post to their Facebook page this morning.

'It's that time of year again when we are wrapping up our annual cannabis operation. While many of you think it's god's greatest gift to us, it is still illegal which means we still police it,” the post reads.

'Rather than hitting you with stats and "don't do drugs" comments, we thought we'd take a lighter approach and run a competition.”

But those worried for the cows health, police were also quick to point out they know cannabis is potentially toxic to animals and the plants were taken off the cows 'well before they could enjoy their high tea”.

In the first hour of the photo being published online Waikato District Police's post attracted 159 comments.