Defecating. Shitting. Dropping a deuce. Taking a dump. Laying a log. Especially when used to describe it in a relaxed state or a break from life.
Classmate A: " dude uve been gone for like 15 minutes u missed half of 3rd period where were you?"
Classmate B: "dude i went to the bathroom i was steaming, man it was life changing."
Classmate A: "wow man im jealous maybe next class ill get the same delightful experience."