The meaning is that the person who you are speaking to must have had your big dick right in his/her mouth.
Steffan had di bi di i ur mouf! What the fuk is that popping out of his mouth?! o dats my bi di i his mouf!
by Pimp daddy July 08, 2004
Get the di bi di i ur moufmug. 
by @BeignetPapi May 25, 2022
Get the Di di’smug.