ludicrous, silly, farcical, humorous, derisory, humourous, foolish, pathetic, undignified, preposterous, more...

sensible, reasonable, logical, rational, serious

absurd, preposterous, ludicrous, laughable, silly, farcical, absurdist, absurdity, more...

"that's absurd!",   totally silly,   absolutely absurd,   very silly,   like some farces,   dumb idea,   purposely absurd,   very foolish,   silly stupid,   looking foolish,   foolish; senseless