ditziest

/ˈdɪtsiɪst/
adjective
  1. The most silly, scatterbrained, or least serious; superlative of ditzy.
    • That was the ditziest idea I've ever heard — it would never work.
    • She was the ditziest character in the play, always tripping over her own feet.
    • Among all the contestants, he was the ditziest, forgetting his lines on stage.