Lol, I like that.
I kinda did it w/ my old sleeping bag once when used like a pea pod. I used it to help hold the bottom up against me and keep the opening from letting all heat evacuate. It worked OK but I wasn't a fan of the pea pod method and my bag was wayyyy too heavy to really be usefull for anything other than car camping. Have slept much more comfy and warmer w/ the IX UQ.