Appalachian/Southern Slang for digital-anal intercourse. Usually associated with adolescent male rite of passage, similar to counting coup.
Growing up in Blacksburg, VA, the Paris of the Appalachians, there were basically two sets of kids. I'm about to make a classist statement, but please consider it as cultural anthropology instead of me being a prick. There were the Professors' Kids (from Virginia Tech) and the Townie Kids, the locals - pure product of the Blue Ridge Mountains. Needless to say, this made for some interesting syncretistic culture and culture clashes.
For the most part, once everyone got to High School, a solid de facto caste system was in full effect. P-Kids took "college bound" classes, and T-Kids took "Vocational" classes. There was very little social mixing, probably the intended or at least accepted result all along. What interface did occur happened in the sports programs. Mostly it was the football team, but there was one townie who played fullback on the soccer team.
Our Soccer team was known to be a rough bunch. They played dirty as hell and imagined themselves to be some kind of roving band of villains. Since soccer shorts are so damn easy to pull off anyway, there was the expected amount of shorting, mooning, etc... With this bunch, the inevitable escalation began to occur. A shorting provoked a mooning. To retaliate for the mooning, there was a close-range mooning. This was followed by "brown eyes" of longer and longer duration.
Finally, in the locker room, one of the Professors' kids climbed up on a changing bench and squatted in the face of Townie and held it, cheeks spread. Without hesitation, the townie wet his middle finger and ran it right up the ass of the professor's kid in question, later reporting that he had, "given it a little wiggle."
The squatter was frozen in place, then sprang away in abject horror. The locker room fell into total silence, being mostly filled with Professor's Kids. It was into this silence that the Townie spoke, laughing:
"What? Haint none of y'all had your oil checked?"
He said it with the nonchalance of someone asking if you wanted milk or lemon in your tea. The room erupted into laughter, this undoubtedly being the most audacious physical "burn" they had ever witnessed in their middle-class lives. I can safely report that it became part of the standard lexicon of physical harassment for the soccer team.