Sometimes the image accompanying the directions is vandalized:
If the diagram includes "waves" signifying warm air, the would be graffiti artist makes notes about "bacon", either drawing a frying pan around it or labelling the diagram "Push button, get bacon."
A more common, and far more vulgar version, is to treat the "finger pushing the button" part of the diagram as a target.
The icon is of a lone index finger (extending from a fist) poking inside a circle.
By drawing a vulva around the circle (making it a vaginal hole), or even going further beyond and drawing a spread-legged woman around it, it would appear to suggest a form of digital stimulation or "fingering" directive. There are obviously other variants, including drawing a man on all fours from the rear around the button making it appear to suggest one is to do a prostate exam on someone or engage in some form of anal masturbation of another.
In Texas I saw one which suggested doing these things to an animal by drawing a cow around the button, but whether the finger was meant to be inserted into the cow's anus or vagina was unclear. It's part of the vicissitudes of predator pressure setting the rhythm that the would be Sharpie artist has at best minutes to complete his or her masterpiece.