Vinny Castilla used a large animal bone to strengthen Gerardo Parra's bat

On Tuesday afternoon, Rockies veteran outfielder and bold-haired individual Gerardo Parra posted an odd-looking video to his Instagram story. The video appeared to show former Rockies third baseman and current Rockies special assistant to the GM Vinny Castilla pushing a baseball bat against what looked to be an enormous animal bone.

While at first glance this may look bizarre, Castilla and his still-ripped-despite-retirement forearms were actually practicing a well-established baseball craft called "bat boning."
Jorge Castillo of The Washington Post wrote a phenomenal explainer of the technique last year after a few of the Nats, including Ryan Zimmerman, tried it out.
Basically, it works like this: Bats made out of ash wood are less dense than bats made out of maple and therefore come apart easier. By rubbing these ash bats against a large sturdy object, players are supposedly able to coax a longer shelf live out of their lumber.
Who knows if bat boning actually works, but at least we got this photo out of it.