From the ArcaMax Publishing, Vocabulary Newsletter:
http://www.arcamax.com/news/vocabulary/s-568858-405095
flippant \FLIP-uhnt\ (adjective) - Lacking proper seriousness or
respect; showing inappropriate levity; pert.
"Ann is flippant where I'm serious, and I'm flippant where Ann is
serious." -- John Cowper Powys, 'Wolf Solent'
Flippant probably comes from flip. The noun form is flippancy.