There is a little thingy (or two) that is available for sale in
Pilot Shops for use in small aircraft that do not have Toilet Facilities.... Essentially anything short of a corporate jet will not have those facilities.
The thingy ...A WEE WEE Pot....(Available in both Male and Female versions) is much like the little thingy you are provided when in Hospital when you can not ..or do not feel like getting out of bed.
I've NEVER seen one of these for boats.
I totally apologize for this Trivia.

NB
EDIT: For those who have an insatiable curiosity:
http://sportys.com/PilotShop/category/930 Check ALL FOUR Products.