Has an AFL game ever ended 100-99?
Yes. AFL has seen a final score of 100-99 5 times. It first happened on April 21, 1928, when Sydney beat Footscray, and most recently on August 6, 2011, when Essendon beat Sydney.
That makes 100-99 the 589th most common final score out of 6,607 that have ever occurred in AFL. One point away, 101-99 has happened 3 times and 100-100 has happened 2 times. At one point the score disappeared for 54 years, between 1951 and 2005.