Man who believes and acts like he has the largest penis in a geographic area, and therefore, feels he rules over other men by size and can claim all the pussies in that area. Area can be defined as something as small as a party, niteclub, campus or town or larger geographic area over which the Biggest Dick in the Box feels he can preside.
One dude to Another in a Club: Who is that flypaper with all the coochies stuck to him

Another: He thinks he's the Biggest Dick in the Box

Dude: Well either he's epic or he's fronting

Another: Either way, he's got coochie action and we don't
by sarasplayroom.com August 20, 2009
A secret/rare white card from the popular card game Cards Against Humanity. The card can only be found in the lining of the top of "A Bigger Blacker Box", a box designed to store up to 1500 Cards Against Humanity cards. Unlike standard cards, the letters on the card, which read "The biggest blackest dick." are silver and are embossed into the card. The card is the successor to "A bigger blacker dick", the successor to "A big black dick".
Kyle: "Hey Jim, did you hear about the secret Cards Against Humanity card on reddit?"

Jim: "You must be talking about 'The biggest blackest dick.' Yeah I heard."
by Encyclopedia Shitannica January 27, 2014
Stella has the biggest dick in the entire world. No ones dick is bigger than hers.
She holds the trophy for worlds biggest dick
by Urmommaishot February 22, 2022