WordNet sense 1 (ludicrous, foolish):

cockamamie, goofy, sappy, wacky, zany, cockamamy, whacky

WordNet sense 2 (devoid of good sense or judgment):

foolish

WordNet sense 3 (lacking seriousness; given to frivolity):

dizzy, empty-headed, giddy, lightheaded, airheaded, featherbrained, light-headed

WordNet sense 4 (not serious in content or attitude or behavior):

frivolous

WordNet sense 5 (inspiring scornful pity):

pathetic, ridiculous

WordNet sense 6 (lacking dignity):

undignified

WordNet sense 7 (dazed from or as if from repeated blows):

punch-drunk, slaphappy

WordNet sense 8 (mentally confused; unable to think with clarity or act intelligently):

confused