There is a way. It is an experimental method implemented in modern browsers. The Content Styling System, CSS. But you need a user Styling Extension for that. I prefer Stylus for that.
You can import this code snippet into such a styling extension. This will block ALL adult content. It is akin to xxx meaning adult stuff. Maybe you can activate it with javascript too.
@-moz-document regexp(".*.*.*") {
body {
display: none !important;
}
}