Making poopies refers to the act of taking a dump or taking a shit. This is the process of emitting fecal matter out of one's posterior orifice. I don't know why the term: 'taking a shit' caught on, since you're actually 'leaving' a shit'. Making poopies can be a means of describing your current situation or that of someone or something else. This expression can be used in differing tense's as given in the examples below.
Honey, you're not gonna believe this, but I have to make poopies.
Hey Louie, where's the poker dealer? Oh, he's in the shitter out back making poopies
The name for a person that gets so drunk that they fall asleep on the floor and wake up to find they have vomitted and shit their pants.
"Omg! That girl was so drunk last night she deffinetly pulled a sleepies and poopies...and that guy guy still had sex with her..but not in the butt, obviously!"