Abuja - It's rude to eat in front of someone else who is not partaking. On the other hand, nobody expects you to share your toasted sandwich should they walk in on you grabbing a quick bite to eat in the office.
Unless you want the other person to sit down, stand up (or at least make like you would like to, were your lap not filled with food particles of varying sizes), and ask if you can get back to them when you're finished.
Give a time-frame, and stick to it. Try: "I'll be finished in another 10 minutes and will come by then."
There are a few other caveats to remember.
Your lunch should not smell so much it attracts attention, negative or positive. It's not bait for a visit. Nobody should be able to hear you chomping it, either, or slurping your soup or beverage. Otherwise, you may well end up the brunt of office jokes, and deservedly so.
When the office has a communal kitchen, some rules for peaceful coexistence should apply.
First and foremost spell out who is in charge of the kitchen and has the authority to determine when and how it is cleaned. Post the rules clearly (together with whatever rule you might have about kitchen postings). Is the refrigerator door fair game for announcements beyond the cleaning schedule?
If it is off limits, let everybody know that that is the case. Otherwise the next thing you know it will be festooned with family photos, want ads, for sale signs, etc.
Refrigerators need to be cleaned out every week, and food should not be stored there over weekends. Never bring smelly food to the fridge in the first place.
Whatever you bring, make sure it's in airtight containers labelled with your name. More than likely, there will be some unlabelled food; do not consider this fair game for you to scarf up (or down, as it may be). When in doubt, ask.
Better still, if you are bringing something in for the entire department to enjoy, put a note on it that says so.
Don't be a space hog, monopolising the fridge with your colossal container that is sure to flatten everybody else's focaccia. And make sure to close the refrigerator door.
If, although your lunch had been clearly labelled, some fledgling criminal element has stolen it, ask around without making a fuss. Give the miscreant the benefit of the doubt - this one time. Mention it to your department head, without mentioning names of potential suspects so that it can be brought up at the next office meeting.
You also could send an interoffice e-mail or text with a little humour (at least the first time), offering a reward to the person who brings the goodies back, no questions asked.
Keep it clean
Microwaves are not for cooking at the office. They are only for heating food, so don't monopolise them, and don't walk away and leave them while something of yours is being heated.
Wipe off the exploded pieces of casserole as soon as you discover that you forgot to cover the dish.
Be careful what you prepare so that your food doesn't leave the entire office redolent of eau de popcorn, or worse. In fact, some offices have rules against popcorn because of the smell and also the likelihood of setting off the smoke alarm.
Many offices are using single-serving coffeemakers. While this eliminates the hassle of who cleans the coffeepot, it still means that whoever drinks last, cleans up after himself and gets the machine ready for the next person.
So dispose of the used container, and be sure to wipe up any drips. If your office has a regular coffee pot, the same consideration applies.
The Boy Scout rule
The well-known Boy Scout rule to leave the campsite cleaner than the way you found it can and indeed should be applied to office kitchen sinks and counters.
Crumbs, human or otherwise, have no place on counters or in the sink. Wash your own mug, plate, silverware, glasses, and put them in the drainer right away. No fair leaving dirty dishes in the sink. If that doesn't work with your mother, you can be sure that it won't fly with your co-workers.
Whether it's your desk, the office refrigerator, the coffeepot, the counter, the sink, or the floor: if you spill something, clean it up. Your colleagues are not your servants; nor are you theirs.
Think égalité and fraternité; you may choose to ignore the accents, but you must be accountable for the accidents.