Every single Thursday, social media users post old photos to Facebook, Twitter, and Instagram. Why? Because it's #ThrowbackThursday! It's unclear when #TT officially became a thing. But it's clear that people from all walks of life have fully embraced it. And that includes athletes. Just check out the list of the best Throwback Thursdays from athletes that Bleacher Report created over here. Ah, the good old days!

[via Bleacher Report]