Slang for the word "duct", as coined by famous youtuber FlightReacts in his universally panned song "Cold-Blooded" (which also rips off the hook from the Lil' Boosie song of the same name).
Flight: "So niggaswanna DUT tape us 'cause we cold-blooded.."
Anyone with a functioning brain: "Nigga wtf is a dut?"
Dutt, anyone who is utterly and outrageously stupid..
In reality, whoever says it is the idiot.
It means that they have no other comeback or just say it because they think it sounds cool in their tiny brains where the word 'Dut' is 'cool'
Person1: He's such a dut
Person2: You know how stupid you sound when you say that ?