Definition

"Goddamn Girlfriend"—a texting abbreviation for when you're too frustrated with your romantic partner to type out her actual name because that might show mercy.

Example Usage

Sorry I can't make poker night, GDGF is being unreasonable about me gambling again.

Source: Urban Dictionary (https://www.urbandictionary.com/define.php?term=GDGF&defid=8127831)