In the book "Where Do Nudists Keep Their Hankies: And other naughty questions you always wanted answered" there is a chapter on old lies adults (page 27), particularly teachers and religious figures, would tell kids in order to get them to not masturbate as it was believed to be the unholy way of wasting your seed. among these lies were
"you can go blind" and "your palms will get hairy"
anyway ill go into it, since i whipped my book out for it.
Quoted in 1760 Samual August Tissot said "L'Onanisme, ou Disseration Physique sur les Maladies Produites par la Masturbation" which is basically aimed to tell boys not to sleep with their hands under the sheets. He then described a "case" where a boy died with sores on his body from masturbating too much.
Anyway I suggest the book to anyone about anything sexual basically. In the same chapter they go on about ways they'd get boys to not masturbate as much and even the inventor of Kellogg cereal was "dead against masturbation" and would do horrible things to his penis....explained in great detail in the book. I shit you not. Totally worth 13$ ;)