If you work somewhere for long enough you will learn to interpret the little signs that the environment is giving you. A streaky line on a printout means the toner needs replacing. If the coffee machine is beeping and its lights are flashing, then someone has got a full house and won the jackpot. And if the air conditioning is working it means that we have moved offices.
One sign that we all should learn to recognise is the presence of a large group of clients. When clients are in the office, staff are expected to dress neatly and behave with more courtesy than is usual (i.e. some). More importantly though, there is a strong chance that there is a catered meeting, and that means free leftovers.
Leftovers from a catered meeting often come out just after most people return from their lunch break, however it is common knowledge that the stomachus dessertus we develop as a child (the extra gastric organ which allows children to be full of broccoli and meatloaf but still have room for ice-cream) matures at adulthood into stomachus leftoverus. This makes it possible for someone to be brimming from a recently consumed lunch and still find room for free chicken sticks and deep fried cheese balls.
If you are privileged enough to actually attend a catered meeting, keep in mind your co-workers who are not. You may be tempted to employ all available stomachs, and eat as much as you possibly can, ensuring the freeloaders get nothing. But remember that you were once like them, eagerly flocking with the other seagulls outside the meeting-room door. You should make sure that something is left behind for them, even if it is just those cucumber and celery sticks wrapped in rice paper that nobody else wants.