The people of Goulburn might get a surprise today when they look up at the Big Merino and see it painted partly blue.

A paint job on the ram's testicles has been revealed today as part of a campaign for the charity, Blue September.

It is encouraging men to get themselves checked for prostate and testicular cancer.

Campaign director Mike Chapman said the Big Merino was chosen because its "boys bits" are highly visible.

"It's just begging to be part of this campaign really," Mr Chapman said.

"It's something we've been talking about for a little while, finally we've been able to use it as a useful tool to get the word out."

The painting was done by a team from a betting agency.

The agency's Will Byrne said the Big Merino was an obvious choice.

"It's so famous around Australia and if you look at the back of the Big Merino it's got a rather interesting set of crown jewels let's just say," he said.

Painting of the Big Merino for the Blue September campaign, September 2014

"What we wanted to do was highlight for men to get their lower regions checked and paint them blue."

He said the company had donated $20,000 to the campaign and was promoting the cancer awareness message to its users.

"Our target audience is the majority of men so Blue September obviously saw us as an ideal partner to approach the topic," Mr Byrne said.

"One in two Australian men will have been diagnosed with cancer at some stage in their life by the age of 85."

It took about six hours to paint the merino's testicles and a slogan, 'Have you got the balls?'

The blue paint will be removed at the end of the campaign.

The Big Merino is located on the corner of Hume and Sowerby Streets, Goulburn.