It's an Onomatopoeia
Based upon the audible sound caused by a high-velocity metal cooking implement, for example a frying pan, sharply striking a person's face in reaction to an exceptionally bad pun.
(and I was spanging BargeArse)
(
Tribs 🦇 ↓ dn ʎɐʍ sᴉɥʇ ↓🦇,
Mon 23 Feb 2009, 0:00,
archived)
or a shovel
they make a wonderful alternative to cooking implements
(
munzor in the jungle,
Mon 23 Feb 2009, 0:41,
archived)