adj. Profoundly uninteresting or useless.
2007
Finally, besides the obvious threat to public safety, the whole text-messaging thing strikes us as a WOMBAT (waste of money, brains and time).
2000
Trying to keep abreast of new terminology might seem, to use Silicon Valley lingo, to be WOMBAT duty — a waste of money, brains and time.
1990 (earliest)
WOMBAT [Waste Of Money, Brains and Time] adj. Applied to problems which are both profoundly UNINTERESTING in themselves and unlikely to benefit anyone interesting even if solved.