Has a College Football game ever ended 81-16?
Exactly once. On November 16, 1974, Texas beat TCU 81-16, and no College Football game before or since has ended that way. When it happened it was a scorigami, the first 81-16 in league history.
That makes 81-16 the 1819th most common final score out of 2,215 that have ever occurred in College Football. One point away, 82-16 has happened never and 81-17 has happened never.