Whether it was on the track in Rio or off of it, Usain Bolt did the most out here during his final Olympic Games.

After securing his triple-triple of a third straight Olympics with three gold medals won, Bolt decided to usher in his 30th birthday by grinding with a girl in a Rio nightclub. One problem — the young lady that Bolt was dancing with wasn't his girlfriend, Kasi Bennett.

Dirty 30, anyone? Welp. Watch this TMZ Sports-obtained footage.

Add this to the photos of the world's fastest man being photographed in bed with a 20-year-old Brazilian student in Rio and Usain might have some explaining to do quicker than he sprints.

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