I don‘t see the argument here. What you describe is sexual harassment and should be illegal.
If person A draws a naked picture and shares it with person B, and it looks like person C, then person C has been sexually harassed?
If you share it with the entire class? In the school building itself? It becomes impossible for the target to not be aware.
The moment someone teases the other it doesn’t matter how many times it’s been shared.
If the person is recognizable, then in many cases it would violate existing nonconsensual/revenge porn laws, which very often are not concerned with provenance but whether its a explicit, a recognizable depiction, and nonconsensual.
(Depending on where it is shared it might, as others note, be sexual harassment as well.)
I'm not trying to say it's ok, but just like the person you replied to, I truly find these things comparable.