The fantastic Morbid Anatomy blog found this picture from an 1845 medical book depicting ‘the Last Stage of Mental & Bodily Exhaustion from Onanism or Self-pollution’ from the days when self-diddling was widely assumed to be a cause of madness.

Of course, you wouldn’t find anything quite so ridiculous as a mental illness described as ‘the last stage of Onanism or Self-pollution’ in the DSM-5, because stages have been rejected in favour of dimensions.
Link to post at Morbid Anatomy.
I, at least, think you’re funny.