Who does this? This is one of my biggest pet peeves around the office, more so than taking the last paper towel and not replacing the roll. Do you think that someone is going to say wow great 1/4 of a bagel that's been man handled, thats exactly what I want! This seems to happen all the time whenever any food is put out. I have news, it just gets thrown away, no one ever eats the left over man handled piece. Would you? If yes then just take it with you. The only time this is acceptable is when two people agree on splitting something and both taking the pieces with them. For all I know that piece landed on the floor and you put it back. Yes this does happen you would be surprised.