The use of sexualization for fast food isn't anything new. However there is usually a clear divided between the product and the person trying to sell it. In this ad the implication of a sexual act and the placement of model and sandwich puts it across the line.
This ad is ok on face value, but becomes questionable once the copy and implications are taken into account. As it over sells a product that had little evidence of actually being able to work. Further more by using one of the most famous cases of a person with HIV as the spokesperson, creates a belief of legitimacy. Even though the use has no know benefits.
While this add has the benefit of being absolutely hilarious, it is questionable on the placement. Though ads are unavoidable in day to day life of the modern age, to put an add that has such personal implications in such a public spot is truly unethical. Though this can be warranted depending on the building, I believe in most cases it is just inappropriate.