A colleague I just met at work has invited me to be their friend on Facebook. I don't want to offend them, but nor do I want to share my candid photos and lousy Scrabble scores with someone I hardly know.

Can I ignore their invite?

"Can I be your friend?" might work as an ice-breaker among small children, but it's not a question you hear often between adults, at least not outside of Las Vegas. Friendship, it is generally understood, is a relationship that evolves through shared interests, common experiences and a primeval need to share your neighbor's power tools.

Rather than inviting someone to be our Facebook friend only after we've become friends in the real world, many of us are using Facebook as a short-cut around all that time-consuming relationship building.

Why bother asking someone you've just met questions about their family, interests and ability to run a farm or aquarium, when you can simply send them a friend request and read the answers in your Facebook news feed? And so we think little of receiving friend requests after we meet someone for the first time at, say, a dinner party.

If you like the person, perhaps because they brought an excellent bottle of wine to the party, then you can accept the request in the hope of further opportunities to sample the contents of their cellar.

If you didn't get to taste the wine because they accidentally spilled the bottle over your brand new party dress, then etiquette experts would probably agree that you can decline the friend request, send them a dry-cleaning bill and humiliate them in a derisory posting to your real Facebook friends.

In the workplace, however, the dynamic is very different. The consequences of offending someone by ignoring their friend request are greater with a colleague you see every day than with a careless dining companion you may never meet again.