I am trying to make a salad but I can't find a knife at my work. Is there a way I can cut the tomato without a knife?
I'd just cut it at home that morning and bring it. If that didn't work out, I'd bring a pocketknife.
I'm sure you can kludge things, but really, ripe tomatoes are one of the worst things to try to cut with a dull knife. It's so easy to make a mess of them, juice everywhere. And even if your tomatoes aren't that ripe, this still seems easier.
(And if I ended up at work with a salad and a whole tomato and no knife somehow, I'd probably just eat it like an apple while I ate the rest of my salad with a fork.)
Gossamer thread works great if you have any handy. Baring that almost any kind of thread will do the job with the right back and forth motion. The tricky part is you usually need three hands for this method.
More likely to be present at most workplaces is paper. Card stock is best, but any weight paper will do if you pull it tight (much like the thread above).
Baring that, bust open your wallet and put your plastic to work. Credit cards are a bit thick, but you could hack at a tomato with one.
If all else fails, order in pizza. It almost always comes with plastic knives. Give the pizza to a co-worker that isn't so hot on salad and keep the plastic-ware for your own use.
I'm seriously questioning suggestions to use common non-foodie objects like office scissors, business cards, keys(!), rulers and fingernails to cut tomatoes. Can you imagine the amount of dirt on those things? If your office does not have a knife, does it have the required facilities to properly clean the above tools to use them for cutting food?
Don't get me wrong, I'm far from a germaphobe and will gladly eat a "just-from-the-field" tomato without washing, but I would rather bite into it than cut it with random office tools.
Cutting it beforehand is a reasonable suggestion, but depending on what kind of tomato you have, it may not be optimal. The better (ripe, tasty, juicy) tomatoes are best eaten right away after cutting, otherwise they will start release juices and will become more soggy and unappetizing.