The Outlast Trials

The Get Down badge is for "Get knocked down 50 times"

Being "knocked down" actually means reaching 0 health and having to respawn. The best way to do this is play in Co-op as your teammate can just revive you.

The optimal way to do this is get to the end of the "grind the bad apples trial" and repeatedly walk into the grinder to die, then have your teammate revive you (this will also help them progress towards the "Sawbones" badge). Repeat this process then swap with your Co-op partner.

Make sure you die the maximum number of times during a trial to speed this up a little.