When to tell and when not to. It’s a tough call, but one you’ll more than likely to be forced to make sometime soon.

Man-on-man friendship comes in various forms. There’s your old university roommate. There’s the guy on your street who shares your interest in vintage motorcycles. There’s the tight group of fellows you’ve known since your spitball days in middle school. Then there’s your co-worker, your brother-in-law, the dad of your son’s best friend – men with whom sundry twists of fate have tossed you together in a great big salad of comradeship.

When you and your buddies get together, you do what buddies do. You drink your brew of choice, you talk career, family and politics, you play soccer or cards or the stock market. Chances are, you don’t spend much of your pal-time waxing philosophical about the depths of your friendship and where the lines of loyalty might be drawn should certain circumstances arise.

As anyone who’s ever watched the Jerry Springer show knows, however, these circumstances do arise. And more often than we might think. People have secrets, if Springer’s guests are any indication, and those secrets get discovered, often with unpleasant consequences. These kinds of circumstances may soon force you to examine the bonds of your buddyship and make the sort of tough decisions that daytime talk show hosts and ethics columnists alike rely on to cover the mortgages on their vacation homes.

Here’s the thing: sometimes you happen on a tip. A serious tip. A tip that, if you tell your friend, will surely bum him out – or break his heart.

Maybe you’ve found out that your mate at work isn’t getting the promotion he expects. Or you happen to know that the tools your friend loaned to a neighbour have been lost. Or maybe you’ve even learned that your pal’s longtime girlfriend has been with another man.

So, do you hit your friend with what you know? Most of us want to be in relationships based on honesty. But is sharing this kind of information always the right thing to do?

There’s no neat answer. If these situations were a cinch, we wouldn’t be grappling with them. In fact, the agony we put into a decision like this is probably what makes us a good friend. Only an insensitive louse would blurt out bad news without considering his buddy’s feelings first.

Think of it like a math problem. On one side are assembled any reasons you have for telling: for one thing, he’s your friend and telling may be in his best interests – perhaps he’s turning down a kick-ass job offer somewhere else because he doesn’t know he’s about to be unemployed. Maybe it’s even for the good of his loved ones: what if you saw his daughter careening around town without a seatbelt, while treating the family Volvo like a prop car from 2 Fast 2 Furious?

On the other side of the equation are all the compelling reasons for clamming up.

“Things change,” says Ellie Tesher, an internationally syndicated advice columnist based in Toronto. “A promotion decision might be reconsidered. Or the borrower of tools may buy a new set to return.”

You may also have an obligation to keep your mouth shut. What if your employer told you about your office pal’s pink slip in strictest confidence? What if the girlfriend with the cheatin’ heart also happens to be your good friend?

Then there’s the argument that, quite frankly, it’s none of your business. That you don’t fully understand the situation. “But that can be a cop-out,” warns Macdonald. “Being close friends means making your friend’s business a little bit your business. If we care about someone, we look out for their interests.”

Most important when deciding to tell or not is being brutally honest with yourself about your reasoning. “Some people don’t like the idea of having to give bad news, it doesn’t matter who it is,” says Richard Shore, a clinical psychologist in Winnipeg. “Then, it’s not about the friendship.” Face it, it’s a lot easier to talk about last night’s hockey scores than the uncomfortable fact that you’ve spotted his soulmate sucking face with a stranger.

Ask yourself, too, if you’re holding back because you’re fretting that your friend will shoot the messenger. It could happen. But you have to wonder about the friendship in the first place if your pal ditches you just for trying to help. Plus, as Tesher points out, “If it’s discovered that you held back such important information, that, too, could end the friendship.”

In the end, you can’t predict the full impact your decision will have on your friend. But if you’ve done your damnedest to look at both sides of the equation, you’ve done the right thing. And if things turn out differently from what you expect? Cut yourself a break.

“You’re a fallible human being, and you’re going to make mistakes,” says Shore. “You need to be able to forgive yourself and move on.” And even if your friend doesn’t forgive you for whatever problems your honesty may cause, there are plenty of advice columnists out there who’ll stick by you, if only from afar.