Running in just underwear and shoes to a Delta Gamma sorority house and then leaving underwear on the anchor or lawn if no anchor is available. After underwear is removed, participants run back to starting location in their shoes.
I barely made it away from cops during that AnchorRun.
When a SWAT team, or military unit shoots a terrorist, they move on to the next room. To prevent a wounded person from getting up, a shot to the head 'anchors' the body. Any units entering the room will ALSO anchor shot, just in case. (Body might be found with one to the chest, and six holes in the head, just because.)
(Rumored to have started with Israeli Anti-terrorist units.)