A vital topic.
THAT is a classic "hidden" (or not so!) ad. They were very common in the 70s. Remember, anyone, the Triumph TR7 ad for its somewhat phallic car: "The Shape of Things to Come?" And of course every roll-on deodorant bottle is phallic. I remember being shown an ad of a glass of iced whisky that had been altered so that there was a couple having sex drawn in the pool of whisky on top of one of the ice cubes.