Jings, crivens and help ma boab, hev ye no heard o' a oner afore?
Yer wot? err wotever.
Jings, crivvens (with a double v, please) and help ma boab were the standard ejaculations (oo-er, missus) of Oor Wullie
and The Broons
as draw by Dudley D. Watkins for the Sunday Post from the 30s to the 60s. The origins are obscure, but it's most likely that they were east coast, since Watkins, an Englishman, worked for DC Thomson in Dundee.
Probably, therefore, "Jings!" and "Crivvens!" are sanitised forms of "Jesus!" and "Christ!". See also: by jingo, crikey, jeeper creepers and so on. "Help ma boab" may have been invented by Watkins, but is not thought to be related to Fat Boab who was, along with Soapy Soutar and Wee Eck, one of Oor Wullie's bosom chums.
Para Handy won't help you with any of this since it's written in the West Coast and specifically West Highland dialect of a hundred years ago.
Mind you, I'd have said "oncer" myself.