Place said speaker in a mesh laundry bag large enough and strong enough to hold it. Use said bungee cord (see picture in previous post) to hang the filled bag from the ceiling using a plant hanger hook screwed into a joist (you may need a stud finder - my wife found one without one of those electronic marvels btw
nudge nudge). The speaker wire should keep the bag from rotating and swaying to the beat, just make sure the weight is on the bungee.
Dont' laugh, I did this for my brother and two years later it still there working fine.