It can, there's a little ring behind the lens that you can pop out, which makes it about f/10 (details here). IIRC Randy pops that out and glues a washer to the aperture arm, thus making it actually effective.
Originally Posted by jstraw
The hole in the metal shutter plate is f/8 (well, f/7.9, but whatever), so depending on how Randy drills the plastic and what size washer he uses, f/8 and f/11 are probably as right on as you're going to get with a Holga.
Though, even if they are, Holga have some really funky stuff going on, because f/8 at ~1/100 on a sunny day should completely blow out ISO 400 film, but it's just about right. I did some tests on the lens--info and discussion here--but found nothing that made any sense to me.