facetiously

from WordNet (r) 3.0 (2006)

facetiously
    adv 1: not seriously; "I meant it facetiously" [syn:
           {facetiously}, {jokingly}, {tongue-in-cheek}]

from The Collaborative International Dictionary of English v.0.48

Facetious \Fa*ce"tious\, a. [Cf. F. fac['e]tieux. See
   {Faceti[ae]}.]
   1. Given to wit and good humor; merry; sportive; jocular; as,
      a facetious companion.
      [1913 Webster]

   2. Characterized by wit and pleasantry; exciting laughter;
      as, a facetious story or reply. -- {Fa*ce"tious*ly}, adv.
      -- {Fa*ce"tious*ness}, n.
      [1913 Webster]