Usain Bolt achieved the triple-triple in 2016, completing three Olympic gold-medal sweeps in the 100m, 200m and 4x100m relay. He completed the feat at the Rio de Janeiro Olympics, having already won all three events at Beijing 2008 and London 2012.
In Rio, Bolt won the 100m in 9.81 seconds and the 200m in 19.78 seconds. He then ran the anchor leg for Jamaica in the 4x100m relay, helping the team win in 37.27 seconds. Those victories made him the first athlete to win the Olympic 100m and 200m three times, and they secured his famous “triple-triple.”
There is an important later complication. In 2017, Jamaica’s 2008 4x100m relay result was disqualified after teammate Nesta Carter’s retested sample was positive for a prohibited substance. Bolt therefore lost that relay gold medal in the official record, reducing his Olympic gold total from nine to eight.
Despite that retrospective disqualification, 2016 is the canonical answer because Rio was when Bolt completed the feat as it was originally achieved and widely reported. The term usually refers to his three-event sweep across the 2008, 2012 and 2016 Games.