"When I saw the poster for the first time on my way to work, it made me so angry. It doesn't get more tasteless than that," said Hilde S (not her real name), who works as an interpreter.
The 49-year-old finds it particularly offensive that children are being confronted with an image showing male genitalia - so as soon as it gets dark she arms herself with spray paint and paints a black mini-skirt onto the model.
"I don't care if anyone sees me. I think you have to take action when certain elements of society don't have a modicum of decency and taste," she told Heute newspaper.
The Advertising Council has had over 100 complaints about the poster so far - but has said that as it is an artwork by American photographer David LaChapelle, it is not responsible for it.
Hilde S has vowed to continue with her spray painting - "I just can't help it!"
The Local spoke to people in central Vienna to find out if Hilde's disgust was widespread.
Bryan, visiting Vienna from Maryland in the US with his wife said, “I saw the posters but didn't know what they were advertising. I figured it was for an art exhibition or something. We knew that Vienna was an arty place. It’s fine for us, but we would have a problem if we were here with our children.”
Vienna resident Janine wasn't bothered: "Posters for the Vienna Life Ball are usually artistic and beautiful - this is the first more provocative one I've seen. But I think it’s absolutely no problem to have this up in a public space. If children see it they would probably just think it’s funny.”
Jens, a German visiting Vienna with friends, thought it was appropriate in the circumstances: “This poster is absolutely fine... when advertising an event like the Vienna Life Ball. I have children and I would have no problem walking down the street and them seeing this poster.”
Chris, a Vienna local, said he didn't have a problem with the poster, "although I have a 10-year-old son and it would be harder to explain it to him. My parents are in their 70’s and would think a little differently though."
Life Ball organizer Gery Keszler said the poster is designed to communicate a message of tolerance and acceptance, and is not about sexuality - although he did hope that it would be provocative.
However, Heute columnist Christiane Tauzher writes that she finds it offensive that her children have to see the poster and that "tolerance is not achieved by bashing people over the head with a mallet."
Vienna's annual Life Ball is the biggest charity event in Europe supporting people with HIV or AIDS. This year it takes place on 31st May.