The agency posted a security guard-type character outside the West End Donor Centre in London with a "gay detector" to scan men on their way into the centre to determine their level of "gayness". A hidden camera captured the reactions of the lucky gents.
The Gaydr device – which appears to consist of a toy space gun with an iPhone strapped to the top – supposedly use "homo-erotic tendency technology, according to Laurence Thomson, chief creative officer and co-president at McCann London. A series of Gaydrs devices will be sent to influencers - while a Gaydr test can also be taken online.
The campaign was created by Robin Gordon and Ella Monti, with the film directed by Blake Claridge.
"The point of the video is to highlight the absurdity of the sweeping restrictions and the generalisations about gay and bisexual men on which they are based," Thomson said.
"Our aim is to support efforts to reduce the prejudiced restrictions on blood donations from men who have sex with men and to help patients in need by boosting global blood supplies."
Until 2011, men who had ever had sex with another man were banned from donating blood in the UK for life. Then, after the lifetime ban was lifted, men who had had sex with another man in the past 12 months were still prevented from donating. Last year, this was lowered to three months.
This restriction remains in place. is despite shortages of blood supplies, which puts at risk the lives of anyone needing a blood donation. In contrast, straight people who engage in risky sex are not prevented from giving blood.
Peter Tatchell, director of the Peter Tatchell Foundation, said: "These restrictions may have made sense when first enforced in the 1980s at a time when HIV was primarily affecting gay and bisexual men in the West and when HIV testing methods were less accurate. But long ago HIV ceased to be allied to any particular sexual orientation and the testing of donated blood is now very exhaustive and accurate.
"It is time that blood banks worldwide focused more on identifying and excluding individuals who’ve engaged in high risk behavior – regardless of whether they are gay or straight – instead of making assumptions that all gay and bisexual men are high risk of HIV."