What is 18SG movie?

"18SG" is not a recognized movie classification or term. It's possible you're referring to a specific movie title that's misspelled or abbreviated.

To help me understand what you're looking for, could you please provide more information?

* What is the full movie title?

* What genre is the movie?

* Where did you see this term used?

Knowing this information will help me find the correct movie you're looking for.