Daffy
/ˈdæfi/
Definition 1 of 1
Pro Tip 1/3Colloquial Use
Used more in casual speech than in writing or formal situations. 
When she told me her daffy plan, I couldn't stop laughing.
Pro Tip 2/3Mildly Disparaging
Implies a gentle ridicule without harshness, often affectionate. 
Oh, Uncle Joe and his daffy fishing stories!
Pro Tip 3/3Not Malicious
Reflects behavior that is whimsically foolish rather than ill-intentioned. 
Her daffy sense of humor is what makes her so endearing.