Residents are total scavengers.
One day during my intern year, I was craving caramel popcorn. The cafeteria was only selling massive bags of popcorn, so after I ate a couple of handfuls, I had most of the bag still left. I decided to leave the open bag on the table in the resident's lounge.
I kind of meant for people to take what they wanted, but I figured nobody was going to eat from a random open bag of popcorn. Boy was I wrong. By noon, when I came back to the lounge, most of the popcorn had been eaten. Then when I came back again at three, not only was all the popcorn eaten but even the bag was gone (presumably devoured).
When I was on call in the ICU, someone brought some giant cookies into the ICU physician break room in the morning. I got hungry at some point later in the day, so I broke off a piece of the one remaining giant cookie and ate it. The next time I came into the classroom, a little bit more of the cookie was missing (someone else must have eaten some). I ate a little more too. Each time I came into the classroom, a little more of the cookie would be missing and I'd eat a little more.
So I was sharing that cookie with someone. I just don't know who. And this didn't bother me in the slightest.