You have your bodily functions
Now I've known that some guys will go out in the back of the woods and piss with each other, or something... Pissing I guess goes back to the "marking our 'kingdom'" type of instinct from the Monkey Age's.
Now shitting, is another thing. I don't think shitting is a public event, unless you're one of those SCAT people.
Then we have vomitting. Vomitting is like america's pass time now. College Students, Police Officiers & Con goers alike like to vomit around their friends and it's like "WHOA he vomited...". If you ask me vomit looks & smells worse then shit or piss, and if you're the vomitor it sure as hell feels a HELL of a lot worse then taking a dump or taking a piss.
So Piss = relief(unless you have a STD) Shit = Struggle & then relief, Vomit = Misery and pain and horrible horrible feeling for hours afterwards.
Yet Vomit leads out on social acceptance.. WTF