A word evolved from "damn it" to be used in moments of exasperation and frustration in both joking or serious context. The DUY is often emphasized withy only a hint of, or no pronounced, "mit". Most often used by reilly and devon.
Devonia: Okay, we're at WalMart, but where are the whiffle balls?
Reilly: I guess they don't have any.
Devonia: DUYmit!
Reilly: DUYmi!
Devonia: DUYm!
Reilly: DUY!
Devonia: DU!