I hopped in a cab in front of The Post the other day and asked to go to Children's Hospital. The driver, who was a black American, made a U-turn, went north on 15th Street, zipped east on Harvard Street, curled around Howard University and McMillan Reservoir and had me at the front door in about eight minutes.

"Good service," I said, as I handed him the fare. "How did you know that this was the fastest way to go? Most of the time I get drivers who go all over creation trying to get here."

"Been driving 30 years," came the reply. "But I'll tell you what. Some of these foreigners out here, these Nigerians and these guys from the Caribbean, they could drive 30 years and they'd still never know where anything is."

I let it pass at the time, but I'm not going to now. For the last couple of years, I have been hearing heaps of similar gibberish about foreign cabbies, some of it from passengers but a lot of it from their fellow drivers. Ironically and sadly, the most hostile drivers have been black Americans -- who certainly ought to know how it feels to be lumped and type-cast unfairly.

So it's time to remind critics of foreign cabbies of a thing or two.

Thing One: No one drives a cab in this town without passing an exam. There isn't one exam for Nigerians and another for Anacostians. There is one exam, period. To pass it, foreign cabbies have to memorize the zone map and the fare structure and the locations of such obscure streets as Saratoga Avenue and Hughes Mews. They earned the right to be out there.

Thing Two: It costs about $30 a day to rent a cab and $15 a day to put gas in it. That means a cabbie has to gross about $100 a day to make a living. If you're a foreign driver and you don't know the fastest way from Point A to Point B, you will never come close to $100 a day. So it's ridiculous to say that either customers or native-born drivers are being victimized by waves of know-nothing foreign drivers. Know-nothings soon find themselves flipping burgers at the local drive-in-drive-out.

Thing Three: Foreign drivers aren't the scum of the earth, as many of their American detractors imply. Many are students. Others are professionals who are in Washington temporarily to receive special training from U.S. government agencies. Still others work at embassies. I had an American driver not long ago who compared his foreign competitors to "Fidel Castro's boat people -- you know, the dregs of society wherever home is." Nothing could be further from the truth.

If American-born drivers are so threatened by foreign-born competition, they're free to go into another line of work. Failing that, they ought to put the pedal to the metal and stop feeling so bloody sorry for themselves.