Idjit
From Super-wiki
Look after your brother, ya idjit.
"Idjit" is an affectionate, but exasperated, appellation applied by Bobby to Sam and Dean - first heard in 3.03 Bad Day at Black Rock. It has become something of a catch phrase, and Bobby's use of it is imitated by Crowley in 6.04 Weekend at Bobby's. In 7.10 Death's Door, Bobby's dying word to the boys is "idjits", said with a smile.
Following Bobby's death, Garth steps into his role, adopting a number of his mannerisms including using the phrase "idjit", although Dean in 8.06 Southern Comfort insists he misuses it.
Idjit = idiot. It is a southern thing.
Jim Beaver refers to the followers of his Twitter as "Twidjits".