(MONEY Magazine) – Slick is not how my wife would describe my interactions with maître d's. The thought of palming a fifty and sliding it into another person's hand to secure a table without a reservation terrifies me—I'd drop it, or he'd throw us out. Which is why I surprised even myself this year when I was planning a romantic weekend for our anniversary.

I took the unusual step of having my act together—I bought tickets to a Dido concert (my wife's favorite) at the University of Minnesota, lined up a sitter and secretly reserved a room at the Grand Hotel Minneapolis. A couple of days before the big night, I stopped by the hotel with a bottle of Dom Perignon, told the concierge it was our anniversary and asked if she could have the bubbly on ice in the room. On the way out, I fumbled for a rumpled $20 bill in my pocket and awkwardly held it out for her to take, my hand shaking a little. She smiled and took it.

When we arrived for our stay, our room had been upgraded. The champagne was waiting, with rose petals and chocolate-dipped strawberries. Later, the concierge pulled me aside and whispered that Dido had stayed there the night before and left two fourth-row tickets as a tip. Would we like them?

As we drove home the next day, glowing, I wondered what exactly had happened. Was the concierge that nice to everyone? Or had I used a little, you know, grease?

You bet. Greasing, of course, is usually considered the province of mobsters and people who live in ostentatious houses. Not of guys like me—small-town, thrifty, decidedly unslick. But the fact is that slipping cash to the appropriate person can make the impossible possible and ordinary service extraordinary. It can even bail you out on special occasions when plans change or you forget to make a reservation. It's a skill worth mastering.

Point of clarification: There are two kinds of grease, depending on the situation. There's the benign kind, like my tipping the concierge—essentially a big tip in advance for treatment that you hope will be beyond the call of duty. Then there's the more questionable kind, which is, bluntly put, a bribe, meant to buy you an advantage at someone else's expense—like greasing a maître d' to bump you ahead of people who've been waiting longer than you. Decency suggests that you reserve this kind of greasing for true emergencies.

Bob Coluccio, 53, a former professional baseball player who works in real estate in Southern California, recently attended a wedding reception at which the party extended past the time the bus driver had agreed to stay. Faced with turning on the grease or breaking up the event, the wedding party chose the former. "We got him to stay for an extra hour and a half," he says. "It took a C-note, but it was worth it." (In more ways than one: Booking an extension ahead of time would have cost $300.) If the bus arrived late for its next customer, well, weddings happen once in a lifetime.

Restaurants, of course, are the most common venues for greasing. "It's old-fashioned, but it happens," says Manuel Vila, the maître d' at Ambria in Chicago, where he has worked for 22 years. "I don't go that way—if I don't have a table, I don't have a table. But in that respect I'm not the typical maître d'." Sam Than, the manager at Atlanta's exclusive Pano's & Paul's restaurant, says diners routinely offer from $20 to $100 for a fast table, and he has developed a gentle way to handle it: "I don't think it's right to take a bribe, so I say, 'Why don't you keep that for now, have a drink, and I'll do everything I can to take care of you'—which I would do for any guest—'and later, if you feel I've taken care of you, give me a tip.'"

When hosts do accept bribes, they risk getting fired. Why would they do it, then? Because to someone earning service wages, 20 bucks is big. "Rebecca," a former hostess at New York City brunch spot Sarabeth's, admits that she sometimes bumped people in line for a $20 bill. "It was awful, but when you're making nothing, money talks," she says. (Management, she notes, didn't know.)

No one knows the value of grease better than a former greasee. Emilio Muscelli, 82, was once maître d' at The Sands, one of Sin City's first casinos. In the 1950s, seating for shows by the Rat Pack and others was at the discretion of the maître d', and grease accounted for a larger portion of Muscelli's income than salary. (Today seats for Vegas shows are reserved, but greasing hasn't entirely disappeared.) Muscelli himself is an active tipper—"but only when the recipient has the power to help him without stealing," says his son Perry, a real estate broker. "If there's an extra seat, he gets it. He was in the hospital recently, and he was tipping the nurses. His room was full of nurses."