Idjit
Look after your brother, ya idjit.
File:Bobby.gif
300px
"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.
Jim Beaver refers to the followers of his Twitter as "Twidjits".
Idjit = idiot. It is a southern thing.