The first thing I would do on waking up as my avatar is to panic at the fact that I can't breathe! A bit of stumbling around would let me find a mirror and notice I had been turned into a blank featureless mannequin without a mouth or a nose, explaining my lack of breathing ability. That said knowing why I couldn't breathe wouldn't change the problem, so I would continue panicking until I passed out from lack of air shortly afterwords. Unless someone were to find me and fix my breathing issue shortly after that I would suffocate to death.
And now that finding this thread made me realize how much fridge horror there is in the default avatar I'm actually thinking of getting one. I know I still have an old avatar someone made me for an online game I used to play (A zombie survival game called
Die2Nite), I can just use that if I find it.
Edit: Found it and changed to it, the source is
Zeke from Highschool of the Dead. Slightly altered to fit in with my "guild" from the game of course.