The Collaborative International Dictionary of English v.0.48:

dilly \dil"ly\ (d[i^]l"l[y^]), n. [Contr. fr. diligence.]
   A kind of stagecoach. "The Derby dilly." --J. H. Frere.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

dilly \dil"ly\ (d[i^]l"l[y^]), n.
   something remarkable, highly unusual, or exceptionally
   effective; as, a dilly of a movie; when I make a mistake,
   it's a dilly.
   [PJC]