This will never become a thing, I made this to test my editing skills.

We also need a spoiler filter

what even is nsfl

Not Safe For Life.

Usually used to for content that's not only restricted for age, but also by the viewer's sensitivity for anything graphic or similar 'testing' content.
Also called "shock" content.

Most common forms of NSFL stuff on the interwebz would be gore, extreme or violent pornography, torture, criminal violence, fatal road accidents... You get the idea.

But like
Why would anyone post this?

Imgflip doesn't allow anything of the kind, or anything close to that.
Which is why OP suggests that it would never be a necessary feature.