True "locks" don't arise often in football because the Las Vegas oddsmakers are too smart. They will almost always know when a game figures to be a mismatch.

But there may be one special kind of exception, a friend of mine pointed out recently. "Remember the l979 Independence Bowl?" he asked. I did not.

"Syracuse was playing McNeese State, an unbeaten team that nobody knew anything about. There hadn't been a point spread posted on one of their games, and the bookies had to be guessing when they made Syracuse a two-point favorite. I thought at the time that if you had seen both those teams play, you could have known that one of them was a cinch. Syracuse was; they won big.

"Well," my friend continued, "I think there's a bowl game like that again this year. There's a mystery team that the bookmakers don't know anything about, but this time I've seen them play. I'm tempted to bet $100,000 on the game and be prepared to leave for Iceland in case I blow it."

I don't think he will need to pack his parka today. Any rational analysis of this evening's Tangerine Bowl suggests that the betting line is very wrong, and that the mystery team, Southern Mississippi, will whip Missouri, easily covering the spread, which is 2 1/2 to 3 points, depending on where you shop.

The Golden Eagles haven't had any national television exposure; there hasn't been a betting line on any of their games this year. My friend, whose opinion on sports I respect highly, ranks as an expert on the subject since he has seen them play once. He reported: "They may be the best team in the country. They certainly are the fastest team I've seen all year. I saw them play Florida State, which was a pretty good team with some bowl aspirations, and they could have won by 70." (They actually won by 44.)

Cold statistics indicate that Southern Mississippi is an exceptional team. Quarterback Reggie Collier is the first player to both run and pass for more than 1,000 yards in a single season. The team's defense ranked fifth in the country, yielding no more than 14 points in any game. While its schedule is something of a hybrid between big-time and small-time, Southern Mississippi didn't compile these figures just by playing patsies.

The Golden Eagles went to Tuscaloosa and tied Alabama, 13-13. They beat bowl-bound Mississippi State. They crushed Florida State, 58-14, a victory that seemed to assure them of an unbeaten season and a bowl bid. The week after that heady triumph, the Eagles were playing a mediocre Louisville team that had been soundly beaten by Florida State earlier in the season. It was a classic time for a letdown, and Southern Mississippi suffered a stunning upset.

If the Golden Eagles had won that game, they would be ranked in the top 10 and would be favored by nearly a touchdown in today's game. Instead, they are a mere 2 1/2- 3-point favorite over Missouri.

And what is Missouri? A 7-4 team that nobody could possibly view as one of the best in the country. The Tigers have beaten only two teams with winning records. Their chief claim to fame is a 19-14 upset of Oklahoma, but Oklahoma self-destructed that day by committing eight turnovers. Perhaps a more revealing performance was Missouri's loss at home to Oklahoma State, which showed in the Independence Bowl last Saturday what a mediocre team it is.

Southern Mississippi does, indeed, look like a lock today. This wager was originally intended to be the second half of a parlay with a horse at Laurel, but when that mortal lock went down to defeat two weeks ago, the Golden Eagles became our bail-out bet. If the unthinkable happens and they lose, too, readers need not bother to address abusive mail to 15th Street. I will be joining my friend somewhere in Iceland.