Oh my god, seriously? I just read a tweet about a woman who ate a drippy egg salad sandwich at a lunch interview. Dummy. Two rules about eating "out" or with people who aren't in your family:
1) Know if you have good manners or not (if you're not sure, ask someone who will be brutally honest with you)
2) Order and eat accordingly
If you just aren't sure if you have good table manners, here are some fool-proof ways to ensure you don't make a complete ass of yourself during a meal at which you want to impress. Of course I can't cover the basics of table manners, like not licking your knife and not stacking dishes at the table...there are just too many. But here are some basics to keep you out of trouble, because if you don't know the basics yet, you're probably not going on many interview lunches.
1) Don't order anything saucy or that requires a spoon - not pasta, not gravy, not dressing, not soup - nothing that can drip
2) Eat foods that only require one hand. Yes, you read it right. That means no hamburgers, burritos, or ribs, and nothing you have to cut with a steak knife.
3) Don't use this meal as a chance to catch up on your caloric intake. The purpose of the meal is not to eat - it is to talk, listen, and make a good impression. The food secondary.
4) Don't get a doggie bag - just leave the leftovers on the table. Read #3 again.
5) Use your napkin often.
6) Excuse yourself at the end of the meal and go to the restroom, even if you don't need to "go". Check teeth, wash hands, check for any spare drips, crumbs.
What are safe bets to order, if you're following tips 1 and 2 above? Here are a few ideas:
1) Omelette - can be cut with a fork, not usually drippy, easy to control, you'll recognize everything in it generally speaking
2) Salmon or Halibut filet - not overly smelly, and same traits as Omelette above
3) If you must have a sandwich (breaking rule 2 in first list), make it a turkey or ham sandwich and if the restaurant hasn't cut it in half before serving, start by cutting it in half. These tend to be dryer, more manageable sandwich varieties, I've found.
4) If you're at an Italian restaurant and have to order past (breaking rule 1 in first list), choose the lasagna or something baked. It will be dryer and easier to manage than a saucy spaghetti or fettucine dish.
I hope these tips are helpful for you. And seriously, if you're just not sure if you have good table manners, or you know that you don't, suggest coffee instead of meeting over lunch. And then order a small, plain coffee, definitely nothing with whipped cream!