Last Monday I bet three weeks' pay on Prove The Truth, a colt my speed figures indicated was a sure thing to win the second race at Gulfstream Park.

I watched with anguish as one of his rivals opened a five-length lead, and then with elation as Prove The Truth accelerated and cut into the front runner's margin with every stride. But when my horse's rally fell short by a neck, I was devastated.

I stormed away from the television monitor where I had witnessed this tragedy, and immediately bumped into a horseplayer named Lenny. He was beaming. "That winner had my top figure," he said. "What a standout! I know you must have had him."

Fortunately for Lenny, I have a pacific disposition, for no jury of my peers would have convicted me of assault and battery under the circumstances. Postrace self-congratulation is one of the most serious breaches of race track etiquette.

There are no books of etiquette for horse players, since Amy Vanderbilt has somehow overlooked this area of human activity, so I propose the following guideline. If you have told somebody else whom you like before a race, you are entitled to crow afterwards, and even be mildly obnoxious. But if you have maintained a discreet silence beforehand, be discreet afterward, too.

Another touching question of etiquette arises when a handicapper does tout a friend on a winner, and the toutee profits handsomely as a result. How should he show his gratitude?

Personally, I find offers of money rather crass, but I have no objection to lavish gifts.

Not long ago, a Washingtonian named Mitch visited Gulfstream and I told him that a filly named Dedicated Rose looked like a sure winner. When Dedicated Rose walked home by six lengths, Mitch collected $6,000, and I started thinking that a pair of gold horsehead cufflinks with little diamond eyes might be a fitting token of appreciation. Instead, Mitch opted to pick up half my dinner check that night, and then asked if I liked anybody at the horse track or the dog track the next day.

And I've seen even worse ingratitude. A couple of years ago I touted a friend on a horse in the ninth at Bowie, enabling him to hit the triple for $3,000. I wasn't envisioning gold-and-diamond cufflinks. I merely suggested, "Could you pay me the $300 you've owed me for the last year?"

He looked me straight in the eye. "I'm a little short," he said. "Here's a hundred dollars. I'll give you the rest next week."

If horseplayers can display such selfishness and such gross breaches of etiquette in their dealings with friends, they are likely to treat strangers even worse. Their worst habits often surface in the last-minute scramble to buy tickets before post time, and the revolutionary ticket-selling machines at Gulfstream have given rise to more problems than usual.

At the so-called "Everything Windows," machines punch out tickets of every type and denomination, thus democratizing the wagering process. In the past, a man who wanted to bet $100 on a horse would find himself in line with other high rollers. Now he may have the experience that a horseplayer named Paul did the other day.

Just as the horses were being loaded into the starting gate, Paul decided that the favorite was worth a $100 bet and sprinted toward the nearest window. One man was in line in front of him. "Box the 4-6-7, the trifecta, for $2," he instructed the seller.

"There is no trifecta wagering in this race," the seller said.

"Oh." Pause. "Well, um, give me perfectas 4-6, 4-8."

"The eight is scratched."

"Oh. What should I do?"

Paul knew what he should do after he was shut out and couldn't get his bet down. Unfortunately, he could be arrested for it.