n. Named for the U.S. Army Rangers, an elite group of soldiers.
Commonly done as a military initiation joke, the subject is blindfolded, and two people hold his shoulders down. Another soldier (more commonly one who has been in the service for a while) stands with his pants down so that when the other two release the subject, his face plants right in the standing soldier's ass-crack.

When you eat dirt for the first time and leave your family to build a shack in the woods