Quick Definition: To misjudge (usually overestimate) the attractiveness of an HB for some reason.
The letter “D” in the term “Error by D” can stand for multiple words, including Distance, Drugs, Drinking, Desperation, and (Sleep) Deprivation. The “D” can even represent any word by which an error can be made, regardless of whether or not the word begins with the letter “D.”
The point is, through some form of overindulgence or deprivation, the PUA’s judgment of the attractiveness of a woman has been impaired.
Sorry, that was a fugly girl. Error by D on my part.