Joke du jour

Nine-year-old Lisa was busy keeling on the floor looking for her favorite marble, and her 4-year-old brother Bob volunteered to pitch in... ...
Lisa:"Where is it? Darn it!"
Bob:"Lisa, what does 'darn it' mean?"
Lisa:... (rolling her eyes)
Bob:"That means you can't find it right?"
Lisa:"Uh huh."
Bob:"Darn it!"