I'm not a big fan of Robin, but there are several things that make her adorable.
One Piece 641
The anime version is much better...
One Piece Chapter 711
One Piece Chapter 728
I can't wait for this episode... that look... utterly hillarious
Despite her look, she has her cute side too.
One Piece Chapter 496
Oh, and she wipes it on Usopp's pant... clever Robin!
P/S: The only favourite girl I like is still Nami.