A letter from my granddaughter Betsy, attending her first Girl Scout camp ten years ago, included the brag, "Tomorrow I'll be in charge of the latrine (bathroom)". Explaining the devious terminology with another was apter than she knew, for the word derives from lavatrina, where Romans bathed.
Rowe, R. Robinson
Word Ways: Vol. 10
, Article 13.
Available at: http://digitalcommons.butler.edu/wordways/vol10/iss1/13