For another option, instead of a jack-o-lantern, grab a clearance tank and add a plain pumpkin for a shirt that can be layered all Fall long.
So, I'm slow on blogging today (note, it's mid-afternoon) and so being lazy I'm just loading some of my "tutorial" pics on as-is, no editing, no watermaking, no shrinking to web view size, etc (those of you that blog, don't you think that whole aspect of it can be such a hassle?? - and so I'm skipping it today) - -
Print out a pumpkin shape (or freehand it, but I'm awful at that!) and trace around it on your shirt. Cut that part out.stick a square of fabric under the hole.
Cut some festive socks at the ankle.