"Poopysuit" is also the term used for the blue coveralls uniform worn by bubbleheads while underway. I believe it has a connection to the frequency with which laundry facilities used to be available on subs, hence they got pretty funky sometimes. On ships now, laundry issues are a bit more available.
Not sure how the anti-exposure suits got the name since helos and fighters had no toilets and one would have to be an acrobat to get out of the suit anyway while in flight. Hmmm, maybe that's why.