Following a lengthy session of fingering one's vagina, this is what one would be called if they dug deep in your uterus, hitting your g-spot and beyond; thus, causing the one doing the dirty work to have "joe" (cum, jizz'm, etc.) all over their used fingers.
-Man, Drew is such a player.
-Yeah, I know. He ends up getting some from 75% of the female population of Nebraska.
-Wow. That is sure an accomplishment.
-No. Not really. I heard he's a joe digger.
-Gross. He never washes his hands.