In commercial aircraft there are o2 masks in the lav. You are expected to be in your seat during turbulence, a rapid decompression is an emergency situation, you may be covered in lav juice but you need to be provided o2.
This is not true. In FAA governed aircraft, any chemical o2 generators that can be accessed from inside the lav have been removed. It went into effect early last year.
http://www.airweb.faa.gov/Regulatory...2011-04-09.pdf