Well, it is not a matter of towel-throwing, it is more how the rules are. 90 minutes of regular play divided into two halves, and then one of several tie breakers if the score is currently at a draw. The currently most common standard is a 30-minute extension divided into two halves, then five penalty kicks for each team (taking turns), then single penalty kicks until one team scores while the other misses. There have historically been other tie breakers such as the golden goal (that is to say they continue playing until a single goal is scored or until a time limit is reached, at which point they will proceed with another tie breaker). That is about all I know about association football, though.