I've recently realized that I lack understanding about how to tip.

Of course, I can handle a sit-down restaurant meal without any problem. 15-20% of the check. I get it. Skycaps I can handle, too. My dad always said "a dollar a bag." I've jacked it up to two for inflation, but I know that I'm within the realm of propriety there.

However, many other potential tipping situations have been popping up in my life, which I'm totally unequipped to handle. For instance:

You order a take-out meal from a traditionally sit-down restaurant (say, the Olive Garden, for example). You go up to the bar (usually) to pick up your order at the allotted time, and hand them the credit card. They give you back the slip to sign, and there is a spot there for a tip. They haven't crossed it out or anything. So are you supposed to tip in that situation? If so, how much? Who are you even tipping--the bartender who handed you your food? The cook? I know it can't be a 15-20% tip for a carry-out meal, but what if you only put down a dollar or two (or nothing), and they are grievously offended, and because they know your name from your credit card, they spit in your carry-out orders from now on?

Another difficult situation: cab drivers. I know that you are supposed to tip a cab driver, but how much? (This also applies to barbers and hairdressers as well.) Cab rides are pretty expensive as it is, but are you supposed to tip them a percentage of the fare (which is usually a total rip-off to begin with), or is it a flat rate? This is not merely an academic question since I've occasionally had to take cabs from my home to the airport, and now all those fairly scary guys who I probably insufficiently tipped know where I live.

One final, awkward, potential-tip situation: at my neighborhood Dairy Queen, which I frequent because of an as-yet-untreated Blizzard addiction, they have a tip jar out on the counter. I've pretty much decided that I refuse to tip in this situation, since Dairy Queen is simply a fast food restaurant. I don't tip the kid behind the counter at McDonald's, so I can't imagine why I'd throw extra money at the teenaged, slack-jawed, ice cream jockey who only has to scoop the M&Ms into the Blizzard cup. Still, my steadfast refusal to tip, combined with my habitual darkening of the Dairy Queen doorstep, has led to some uncomfortable glances and silences.

So I need help. When do I tip, and how much?

And don't even get me started on those buffet restaurants where you have a "waitress," but all she does is come by and fill up your water cup. Trying to think that one through is liable to explode my head.