facetious

adj

1. Treating serious issues with (often deliberately) inappropriate humour; flippant.

   “Robbie's joke about Heather's appearance was just him being facetious.”

   “Troutbeck is a tiny village midway between Penrith and Keswick in a very sparsely populated part of Cumberland, and it used to be said by facetious travellers that the reason why it ever had a station at all was to give the engine a rest after it had struggled up the long and trying incline from Threlkeld.”

   “Glamour for its own sake is not something I have ever been particularly interested in,” Stella McCartney said backstage after her catwalk show. Which could sound like a facetious statement from a fashion designer who was, at that moment, standing among the marble-slabbed floors, elaborately frescoed ceilings and giant chandeliers of the Palais Garnier opera house, where the show was staged.”

2. Pleasantly humorous; jocular.
3. humorously silly or counterproductive for the purpose of sarcastically advocating the opposite.