Defecation.
What? Shitting isn't important? Just trust me on this, it is.
Every man needs an impetus. Danny was prey to very few driving forces that would spur him into action, and one of those driving forces was the urge to poop. He's socially foolhardy, but he's even more socially foolhardy when he needs to go. He's prepared to barge into "employees only" areas. He'll even dump in his pants if straits grow dire. And when he's finished, he'll deem it a "good shit."
The scene in the break room features one of the very few face-to-face confrontations Danny runs into on camera. The janitor stomps in, incensed that Danny used such a massive quantity of toilet paper. Whether Danny could rip this guy to shreds isn't clear, but it's peculiar to see him not even try. He's fine with simple trash-talking, which to Danny is as natural as breathing anyway.
Danny really doesn't strike me as an overly violent individual, but again he presents an unwillingness to take any guff. That's admirable to an extent, but still more admirable is the display of restraint that many "normal" people don't have. It may have saved this man some teeth.