"If it's not gay, it's not gay."

The colloquially negative use of the word "gay" is getting a roasting in the first national ad campaign.

"We chose to address something small that contributes to much larger issues — homophobia, biphobia and transphobia," the group posted on Facebook on Monday.

A collaboration between not-for-profit organisation Rainbow Youth, MediaWorks Foundation, Y&R NZ and Eight, the ad has over 90,000 views on Facebook at the time of writing. It focuses on the re-education of a man who ignorantly substitutes the word "gay" as an expletive.

Reactions on Facebook have been both supportive and surprisingly humble. "As someone who says this a lot, unintentionally, as a byproduct of years of not caring/realising... I would like to sincerely thank everyone for their patience and grace," wrote David Phillips under the post.

New Zealand legalised same-sex marriage in 2013, but clearly, socially ingrained homophobic language still exists.