mumblety peg ... which is a form of "chicken" using a knife.
A very old game ... though we played it differently - here's a description from wiki ...
"Mumblety peg is generally played between two people with the aid of a pocket knife. In one version of the game, two opponents stand opposite one another with their feet shoulder-width apart. The first player then takes the knife and throws it to "stick" in the ground as near his own foot as possible. The second player then repeats the process. Whichever player "sticks" the knife closest to his own foot wins the game.
If a player "sticks" the knife in his own foot, he wins the game by default, although few players find this option appealing because of the possibility of bodily harm. The game combines not only precision in the knife-throwing, but also a good deal of bravado and proper assessment of one's own skills"
There are a number of different ways to play ...
They way we used to play though, was to stand as stated above, facing each other at a distance measured by each player putting his arm out in front of himself so that their fingertips just barely touch ... and each player with their feet far apart (kinda like doing the splits but standing up). You would then take turns throwing the knife into the ground between each others feet (not your own feet as in the wiki version above). Usually a standard "spinning" knife throw ... not a spear throw.
The object was to stick the knife into the ground at as close to the middle point between your opponents feet as possible ... your opponent then must bring one of his feet to that spot. Basically you are trying to shorten the distance between his feet by halves with each throw. Occasional adjustments to each other, right or left, are allowable periodically to keep facing each other squarely ... though each player still maintains the distance their own feet are apart.
You win when either you stick the knife between his feet and the blade touches both feet (usually aided by the person "bowing" their feet out to make it a bit less likely of losing a toe), or he "chickens" out. If you actually stick the blade in his foot, you lose. The game works best with a "pocketknife" that has a blade longer than what is "legal" ... a 4" or 5" inch blade on a well balanced, not-too-heavy knife works well. I don't recommend playing this with a sheath knife.
I spent many hours each week playing this in my teens.