Miley Cyrus -- I'm All About PORNO Pumpkins

Miley Cyrus is more trick than treat this Halloween ... at least judging by the photo of some very X-rated pumpkins she just posted on Twitter.

It's unclear if Miley carved the Jack-o'-lanterns herself -- but she's definitely proud of the 3 pumpkins, 2 of which contain images of people bangin' (one lesbian scene) and another gourd contains an image of a giant marijuana leaf.

And to tie the whole thing together, there's a sign that reads, "Happy F**king Halloween."

You stay classy, Miley.