Wiktionary
fat finger
n. A supposed cause of typographical errors.
Usage examples of "fat finger".
Vanin went so far as to mark his place in the book with a fat finger and sit up on the side of his thin mattress.
Pierre quickly took out his purse and watch, but could not manage for some time to get the wedding ring off his fat finger.
The merest crook of his fat finger brought the little man to his side.
Suddenly a red and fat finger was thrust on the form he was filling in.