Welding jargon used to describe the little balls of metal spatter that occur while arc welding. usually these dingle berries just lay around the bead you just made and are easily removed, however, they sometimes stick so that nothing can remove them and your welding instructor calls you a sack of shit jestingly and points out all the dingle berries.
Dingle berries can occur with arc blow, which is magnetism in the metal, and causes the molten weld to spray everywhere but the place you want it. Arc blow causes the most irremovable dingle berries.
As far as my knowledge goes, this term is coined by the finest welding instructor at the SRJC.
Welding Instructor: John Gradren you sack of shit look at all those dingle berries you must of been a mile away from your weld.
JG: But I was using 6013! that shit spatters like no other welding rod.
WI: Alright but next time this happens you're eating the entire bucket of slag and rod stubs.