The print ad for London's leading homelessness charity, St Mungo's, pictures a man sleeping rough in the doorway of a Paul Alexander shop.
In the style of a perfume sampler normally found in a fashion magazine, the copy reads "eau de toilette" at the foot of the page. The ad also features a strip running down the side of the ad that can be peeled back.
However, instead of providing a sample of perfume, peeling back the strip releases the odour of the street and stale urine.
Inside the strip, copy reads: "You're outside. It's really cold. You're starving and there's nowhere to sleep. Do you think the smell of your surroundings is really going to bother you?
"Help a homeless person get off the street. Make a donation to www.mungos.org."
Tanya English from St Mungo's said: "St Mungo's tries to pick up the pieces for people sleeping rough. We offer a complete range of support for homeless people 365 days a year, but we need help from the community to continue our efforts.
"Through your donation to St Mungo's, we will ensure that funds go to the prevention of street homelessness and the support of those who are moving away from it."
The Saatchis art directors Guy Bradbury and Eoghain Clarke created the ad, with the media planning and buying for the campaign was handled in-house.
The campaign, which has an extremely limited budget, will run in the monthly music and entertainment title Word. The magazine is aimed at men aged 35 and over.
Trefor Thomas, the Saatchis creative director, said: "This targeted communication will reinforce that St Mungo's is the leading charity for homeless people.
"This interactive idea communicates St Mungo's message in a relevant yet poignant way, and encourages the community to get involved with homelessness."