Analysis of information sources in references of the Wikipedia article "Mumblety-peg" in English language version.
Mumbly-peg was a version of mumblety-peg, a game in which a jack-knife is tossed in various ways to make it land with the blade in the ground. The loser must draw a peg from the ground with his teeth. The name is derived from the word 'mumble' meaning 'to bite.' The original name was 'mumble-the-peg.'
'The reason they called it Mumbly Peg was that guy was a-fussin' and a-cussin' and all at havin' to dig it [the peg] out of the dirt with his mouth and he's a-mumblin'.'